Don is a retired engineer and long-time motorhome owner who enjoys helping readers deal with the increasingly complex technology of RVs.
How the Generator in Your RV Works
I had a guy ask me one day; "OK, I am not in the least a technical person, so how does a generator work? All I know is if it gets fuel, it runs and I get electricity out of it."
This article will give you a basic overview of the different designs of RV generators, how they operate, and some basic generator service tips.
It will also describe basic differences in gas-powered generators and diesel-powered generators and how they function.
This knowledge may one day help you determine the cause of any generator problems you may have.
A History of RV Generators
In the early days of camping in the USA, there were “rough campers.” For these people, "camping" included a tent, a sleeping bag, a backpack of dried foods, bottled water, a few matches, a snake bite kit, and not much else.
And you know what? I've been there, and I've done that!
It was fun! Especially when I was young, healthy, strong, and had very little money.
And, later in life, when I was first married, and we had kids, I "rough camped" for a while. We camped at resorts, at beaches, and in the mountains. We used larger tents, nicer sleeping bags, inflatable mattresses, a small cooking grill, several coolers for real food, and a few more accessories. And that was fun too, again, for a while!
After a few years, we purchased our first Tag-Along camper. It had rudimentary plumbing, electric lights, storage cabinets, a "porta-potty,” all more comforts for dealing with the vagaries of the weather, and then, of course, we had even more accessories to make our camping more fun.
Those first old campers of ours, way back then, had your basic accessories, such as electric lights, a water pump, a propane stove, but not a whole lot else. They did not have such things as television, air conditioning, hot water heaters, microwave ovens, and all of the amenities that you will find as standard equipment on the RVs of today.
RV and Motorhome Batteries
We owned our couple of travel trailers in the 70's (yeah, way back then) . Probably the biggest problem for us then was that they did not have a generator, just a COACH battery. This battery was usually a deep-discharge 12-volt DC battery that was the same design as what is used in an automobile.
It was usually tied down onto the front end of the travel trailer and was protected from the elements in a plastic case. Typically, you charged the battery up before you left home.
And, considering it only had to power a few 12-volt interior lights, and maybe a small water pump to provide water at the miniature sink, it was a more than adequate power system for a good week of fun.
Over time, as some campgrounds began to provide 115-volt AC at your site, camper manufacturers added small, efficient AC-to-DC converters, so you could charge your camper battery at the campsite.
And once you had an RV with AC as well as DC power, the camper designs used dual-mode light systems (110-VAC and 12-VDC), as well as connections for small appliances.
RVs even began to include showers, electric hot water heaters, larger water pumps, microwave ovens, TVs and multiple wall receptacles for the campers convenience..
RV Battery Box
Appliances for Motorhomes Created a Demand for Generators
The most important electrical addition manufacturers made to RVs and campers was extra electric receptacles, in the kitchen, bathroom, bedroom, and so on.
Once the power was accessible throughout an RV, people started bringing their favorite appliances from home, such as coffee makers, hair dryers, toasters, portable TV's and radios, and on, and on, and on.
RV manufacturers had to react by adding electric breaker panels (versus those old fuses) to handle potential overloads, and heavier wiring for the current all these appliances pulled.
Eventually campers became accustomed to using such appliances everywhere: in state parks, in the woods, alongside streams and lakes, and pretty much wherever they went.
So, the next "necessary item" for the typical modern camper was—you got it—a good electric generator. We all wanted those conveniences and therefore that power, everywhere, all of the time. At the flick of a switch!
Why Have a Built-In RV Generator?
Today, the average RV owner travels much further to reach their camping destination than even a decade ago.
On these longer trips, they often have to stop for the night at an interim campground or two along the way, or do the Wally-World thing (overnight in their parking lot?), or stop and sleep at a rest stop or other public parking lot. And the next morning they eat, pack up, and hit the road for the next part of their trip.
Of course, while on these longer trips they usually have a fridge that is packed with fresh food and beverages, and so they are able to eat very good meals and then sleep in that comfortable bed in the camper.
Myself, I have pulled into a rest area around 6-7 PM, fired up my generator, turned on the TV for local news and weather, eventually cooked a light dinner, and watched my favorite network TV shows, all with the AC running, and finally I'd go to sleep in my nice cool camper, on my own bed.
Often, in a rest area, I will leave the generator running all night, along with a couple of roof fans, recharging my house batteries and providing just enough background noise to drown out most of the outside noise from the comings and goings of other vehicles, campers, and truckers in the rest area.
I will get up in the morning, make fresh coffee, toast a muffin, and boil or fry an egg for a hot breakfast, maybe even take a hot shower, all before I shut down my generator and continue my trip.
Now I have a motorhome, with a built-in generator that is designed especially for the appliances in my RV. It is ridiculously easy to operate. And, often, parked right beside me, might be a Class-C, a Fifth-Wheel, or a Tag-Along, all with their own built-in generators, providing those creature comforts we are all spoiled with. Ain't camping life a rough life?
Portable Generators Came First, Then the Built-In RV Generator
Before camper owners started buying their RV with a built-in generator, many of them used portable generators.
They were convenient, and reliable. But they took up a lot of room when it came to storing them.
And not many models were quiet enough for use at night in a campground.
Because by this time the RV manufacturers knew that they had to do whatever as necessary to make their motorhomes more competitive than the others, they all started installing built-in generators in the larger motorhomes.
So, Now We Can Talk About Generators and Motorhomes
Built-in generators are so popular today that it's actually hard to find a motorhome that doesn't come with a nice generator built into it.
Why only in motorhomes, you might ask, and not in towable campers?
Well, a motorhome already has a fuel source for its engine, so the generator can be fueled by the same tank as the engine.
You rarely see a towable camper with a built-in generator, because to install a generator the manufacturers would have to install a fuel tank as well.
Troubleshooting: Reasons Why Your Generator Might Not Start Up
1. Fuel Supply
Every motorhome manufacturer today that includes an electric generator in their design also includes one little innovation: that is, they no longer attach the fuel line for the generator to the bottom of the RV’s main fuel tank.
They attach it now about a quarter of the way up from the bottom of the tank, so that it will only pick up fuel if the main fuel tank is more than 1/4 full.
This redesign was intended to avoid the situation where a camper out in the middle of nowhere runs the generator until it uses up so much fuel that there isn’t enough left to drive the vehicle back to a gas station and fill it up again.
So, if you are out somewhere rough camping and your generator won't fire up when you turn it on, check that your fuel tank is more than 1/4 full. And if your rig is parked on a slant, the tank may have to be even more than 1/4 full for the fuel level to reach the line to the generator.
2. Oil Supply
Many built-in generators won't start if the oil is down to one quart or less. And that's one reason why you should check the oil in the generator often.
3. 12-Volt Power Switch
To get started, your built-in generator needs power from the 12-volt Coach battery system in your RV. If the power switch to the coach's 12-volt accessories has been turned off, for example to prevent power drainage while the vehicle is in storage, the generator can't get power. Many RV owners don't know where this cut-off switch is. Find it and check it.
4. Fuel Pump or Fuel Filter
If the generator won't run, or runs sluggishly, and there are no fuel, oil, or connection problems, the generator itself may be bad.
But the problem is usually the fuel filter (which can become clogged, especially when using diesel). Fuel filters are common culprits but they are pretty cheap to replace.
Understand How Your Generator Works!
If you use an electric generator, you should have at least a general understanding of how it works, so that you can make sure your generator is there for you when you need it.
First of all, it has to start, easily and quickly. Then it has to run, smoothly, automatically, and efficiently.
Here are some basic facts about generators.
There are four basic functional sections of an electric generator. Of course you can tear a generator down to smaller and smaller working pieces, but I am not trying to teach you to be a mechanic, rather I want you to know how one functions from a high level.
That way you will understand the importance of those pesky preventive maintenance parts in a generator, and why they need to be monitored and even replaced occasionally.
The four functional parts of a generator are:
- a fueled mechanical motor
- a fuel supply system
- an electric starter motor
- an electric power generator
1. The Fueled Motor
Generators are run by a fueled motor of some kind, usually gasoline or diesel, as I have mentioned.
The motor uses the combustion of the fuel to keep the crankshaft of the motor turning.
Today, there are many different designs of motors, from the simple to the complex. An example I can describe here is a simple, cheap gasoline-powered lawn-mower motor with two cylinders.
Each cylinder contains a piston which is connected to a crankshaft. Each cylinder has a fuel input port and an air input port, as well as an exhaust port. The two cylinders are designed so that when one cylinder is firing, the other one is getting fuel and air to fire.
This whole assembly is mechanically designed so that you will get continual firing and exhaust, and the crankshaft will turn from all of this combustion action in the cylinders.
In a diesel motor, there is no spark plug; the combustion is achieved via high compression of the diesel fuel.
One of the most important things to watch is your generator motor's lubrication. Your generator motor uses oil to keep all of those mechanical parts running smoothly as they rub against each other. You should always make sure you have enough oil in the motor, and always change the oil filter on the motor as scheduled by the manufacturer.
Some electric generators are air-cooled. But a larger generator will often have a cooling system similar to an automobile engine, using a water-and-antifreeze cooling liquid.
If your generator is one of these, you need to check the level of the coolant reservoir regularly, and assure the level is kept within the indicated limits. And, as with an automobile, you need to consider the amount and strength of antifreeze appropriate for the season and region where you are using the generator.
2. The Fuel System
Gasoline Combustion: A Simplistic Explanation
A stand-alone gasoline generator gets its fuel from its own fuel tank. The gasoline is usually fed via gravity to the carburetor on the motor. In the carburetor, the gasoline is mixed with air (or oxygen) and injected into the motor's cylinder where a spark is provided via a spark plug.
This spark causes the mixture to explode, and forces the piston in the cylinder to slide open, which moves the crankshaft of the motor. All of this is done via mechanical timing, which keeps the motor turning.
In a coach with a built-in gasoline generator, the functions are the same, but the gasoline comes from the coach's main fuel tank.
Diesel Combustion: A Simplistic Explanation
A stand-alone diesel generator also gets its fuel from its own fuel tank. The fuel is fed via a fuel injection system directly into the cylinder of the motor, and mixed with oxygen there. Then the piston moves to compress the diesel fuel to the pressure necessary for it to explode.
No spark is needed, nor is there any carburetor on a diesel motor. When the fuel mixture explodes, it forces the piston to move to the open position in the cylinder, thus turning the shaft of the motor. This cycle repeats itself via mechanical timing which keeps the motor turning.
Fuel System Service
These parts of a generator's fuel system will need occasional service:
- The fuel filter
- The carburetor fuel jets (on a gasoline motor) or diesel fuel injector jets (on a diesel motor)
- The spark plugs (on a gasoline motor)
If the fuel filter gets dirty or blocked, even partially, then too little fuel will be provided to your motor, and it may not run. If it runs, it may miss or turn off sporadically.
In a gasoline generator, the spark plug will, over time, need replacement. It can become fouled with carbon or dirt, and eventually the contacts will wear out.
If the fuel jets are blocked, then the motor may not run for lack of fuel. If they are worn, the wrong mixture will be provided, and the motor will not run properly.
You can replace a fuel filter, and maybe even a spark plug if it is placed conveniently for you on the engine, but when it comes to replacing the fuel jets you really want a trained mechanic to deal with that.
3. The Electric Starter Motor
Your generator has to be started by turning the motor until it goes through several firing cycles of several cylinders. Once the motor gets going, the starter is no longer needed, as the motor will run on its own.
The starter motor is electric and requires voltage to turn, and in your coach, this voltage comes from your house batteries. It takes a significant amount of current to turn your generator motor, even more with a larger-sized motor/generator combination.
You should also know that because a diesel motor uses a higher level of compression to force combustion, it is harder to turn, and thus its starter requires significantly more current than a gasoline motor to get it to turn at a high enough speed.
The reason you need to know this is simple. There are some hefty wires coming from your house batteries to the generator of your coach. And you should check occasionally to make sure the following things are true:
- Your house batteries are in good shape, and hold a strong charge.
- Your connections to your batteries, as well as to your generator are clean, without corrosion, and attached tightly at each end.
- When your starter turns, it doesn't make weird sounds, and is actually turning the generator motor's shaft.
4. The Electric Power Generator
Here’s a simple description again, this time of the part of your generator that actually generates the electricity.
Picture a coil of wire wrapped around a shaft. This coil of wire spins inside the opening of a larger outer coil of wire. Visualize that the shaft of your generator is attached to the shaft of the fueled motor and turns when the motor turns.
Leaving all of the electro-mechanics out, if you connect a voltage to the ends of the inner coil of wire, and spin it inside the outer coil of wire, and then attach something like a charger or inverter to the ends of the wires on the fixed outer coil of wire, you will get AC voltage from these output wires.
Again, I have left out all of that complex design stuff like the magnetic metals used, the complex ways that the wires are wound, the contacts used, and on and on. I just want you to know that there are parts in here that sometimes require maintenance.
Luckily, the generator itself is designed for minimal maintenance, and if there is a problem with yours, you need to see a trained generator mechanic.
Generator Parts That You Can Check and Service
I will now list the things that can and should be serviced periodically. If you want your generator to last for decades, replace the parts below at the intervals suggested by the manufacturer. Running the generator once a month or so is a good idea.
The fuel pump and fuel filter are the parts that most commonly give trouble. Here's an article with pictures on how I replaced a fuel pump and fuel filter in my Onan 5500 generator.
If any of the terms or abbreviations in use here are new to you, check out my article on electrical terms. It might help.
Tips for Generator Maintenance
With a gas generator, I suggest keeping your old spark plug after you replace it, in case you need one in an emergency.
Keep a spare, just in case, especially if you use your generator a lot.
If the generator is running rough, sometimes you can remove and clean the air filter for better performance, as a temporary solution.
Only a trained mechanic should service this.
Only a trained mechanic should service this.
Check for wear or leaks, especially if you smell fuel.
DC and AC wiring
Inspect wiring periodically for wear, torn insulation, and loose connections. If necessary, get a trained mechanic to replace wires.
Check oil level and change as needed, or when suggested by the manufacturer.
These are easy to change. Follow the manufacturer’s instructions.
Use the manufacturer’s suggested coolant (anti-freeze) mixture. Monitor the level regularly when using the generator, and keep the level within the limits marked on the reservoir.
Comments Are Welcome
Hopefully, I didn't lose you with my attempt at simplifying how an electric generator functions.
If you experience a problem with your generator, check the comments below for troubleshooting tips, and feel free to post a comment about your own issue!
Basic RV Generator Maintenance
RV Generator Troubleshooting
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
Questions & Answers
Question: We can't figure out why the roof air in our motorhome isn't working with our 5000 onan generator while traveling. We know there is a 20 and a 30 amp switch on the generator, and then inside the RV, there are two switches by the door; one switch says main battery, and the other is a diff battery. The air works fine while plugged in at camp. We are new to this RV and camping thing, and cannot figure this out. Can you help us resolve this?
Answer: The two switches are called Cut-Off switches and are used to turn OFF your 12-VDC from your Chassis and Coach batteries, so the batteries do not discharge while the RV is in storage.
Your Coach batteries are used to power your power control panel as well as your temperature control panel and other equipment.
So make sure your Coach batteries are fully charged before you check anything else.
I am pretty confident that your main problem is the charge on the Coach batteries.
Question: In the house battery tray there are two red cables that look like one from the generator and one from the converter/battery charger and then one black cable but all the videos show only one red and one black so should I put the two positives on the positive post together or how should I hook up the batteries?
Answer: With only the information you have given me, I can only assume you have a motorhome that was factory wired with a generator in it.
With this being the case, normally, you would have a wire from the Converter that would connect to the battery PLUS terminal and keep the battery charged when you are operating on Shore AC-Voltage.
There should also be a wire from the House battery that provides power to start the generator.
And there is often another wire connected to your battery that powers your INVERTER.
You will have to trace the wires to determine which is which.
Question: We just bought a new, never used Holiday Rambler Diesel Navigator 38F. The generator is a Cummins, and it won’t turn on, it just ticks. The batteries are brand new and show that the voltage is good, and I have the motorhome plugged into our home. Can you tell me what is wrong?
Answer: Your generator starter is powered by your coach batteries.
Make sure your Cut-Off switch is in the right position to allow power to the interior equipment, and make sure the batteries are fully charged.
Also, make sure the batteries have water in them.
If you just hear a clicking sound and the generator is not turning, then your battery voltage is most likely your problem.
Question: Does a Onan Microquiet 4000 have a fuel filter?
Answer: Yes, the normal configuration of an Onan generator in an RV is to always have a fuel filter on the input fuel line. They are often configured with the fuel filter screwed onto the end of the external fuel pump.
Question: Can you run an Onan generator with the engine off?
Answer: Yes, you can run your motorhome's generator when the engine is OFF.
Your Electrical system in your RV is designed for your generator to support all of your electrical equipment while you are camping at a site where there is no electrical hookup.
Question: I have an RV bus with an onan 7500 gen. The generator starts and runs all of the coach except a/c units. When I turn either a/c unit on the front or back it shuts the gen down in about 5 min. Gen repair shop are telling me my coach batteries are bad. Will that make gen shut down when a/c are turned in?
Answer: If your Coach batteries are not holding a charge then the temperature control panel will lose its 12-VDC power and shut down your AC units. This would happen when your AC units cycled.
I assume the generator repair shop measured your 12-VDC and noticed a sag in the voltage after a while. Check your batteries; 1- how old are they? 2-do they have water in them?
Question: My Generac seized up, so I'm shopping used Onans. Do you think I need to buy the Onan install kit to put it in?
Answer: I would recommend that you get the install kit. Otherwise, if you have problems in the future, you will probably suspect your custom wiring as your culprit when things go wrong.
Question: Our onboard generator starts just fine. I let it run for maybe 5-7 minutes before slipping the 30 amp switch to begin sending power to the appliances etc. They (the coffee maker, microwave), show they are getting power, but then it clicks off. After maybe 30 seconds or a minute, it will look like they are on again, only to click back off again. Do you have any thoughts?
Answer: You didn't tell me what kind or model Rv you have, but most that have a built-in generator has an automatic power sensing system and transfer switch, so I assume you have your 30-Amp Main Breaker turned OFF?
Placing a normal load on your generator should not force it to turn OFF. If your load was too much, then one of your AC-Voltage breakers should have kicked OFF instead. A good generator should operate normally with a load on it.
So, I suggest that you check out your generator as follows; 1-change the fuel filter on the fuel input line, 2- check the electrical connections for any loose wires, 3-If these things seem OK, you should get an electrician to service the generator for you and find the problem.
Question: Can I run the generator on my RV to power an appliance, such as a toaster oven, while I am driving?
Answer: Yes, of course. Your generator will provide power to ALL of your electrical devices when not plugged into external power including a toaster and even your roof AC.
Question: What might cause a new generator in a new camper to turn on, but only run for a minute or so?
Answer: The top two problems with generators in RV's is the fact that they sit for a long time and the fuel filter and the fuel pump both get gummed up.
So, check the filter and fuel pump. They are an assembly mounted under the chassis under the generator, and they're relatively easy to change.
There is also a little secret about generators on RV's. Long ago, many people would go out into the Boondocks and run all of their gas from the RV tank and then not be able to get back to civilization. So, Rv manufacturers would only run the fuel line for the generator 3/4 of the way down into the RV fuel tank. That way the RV owner always had enough gas to get out of the Boondocks. Check that your RV fuel level is above 1/4 tank.
Question: I have a 36-foot leprechaun class C RV with no generator looking to buy a gas power generator 1500 watts starting 1200 watts running will that work?
Answer: The first thing to do is check if your Leprechaun has a space designed for a generator? With some models the manufacturer will design a specific cavity (storage area) for a generator as an option.
If this is true with yours then you are lucky in that you will already have the mechanical strength to support a generator, and you may even be able to purchase the wiring etcetera that will make installation easier.
On the other hand, you could be an owner who will use the generator as their external power source and then you only need a modified power cord.
Be aware that a permanent installation will require some special wiring that switched your RV automatically from External power to your generator.
But be aware that your RV is designed to operate on either a 50-Amp or 30-Amp 220-VAC service. I am assuming that the generator you are looking at using is a 10-Amp 120-VAC capability (10Amps of 120-VAC is all a 1200-Watt generator can provide.-- using the formula Amps-Watts divided by Voltage, or 1200 divided by 120 equals 10)
My point is that this will only power half of your 120- VAC appliance and by the way, your Air Conditioner uses 220-VAC, or in other words 2 separate 120-VAC lines.
Question: does the generator connect directly to the coach battery or to the converter?
Answer: When your generator is turned ON, it replaces your External power source so the internal wiring of the RV is no different.
And, the Coach battery is kept charged by your Converter which operates on your RVs 110-VAC electrical system regardless of which system (External or Generator) is your AC-Power source.
Question: Our R.V. Generac generator has been working fine, but now it will not even turn over; no click, nothing. What can we check to get it working?
Answer: Your generator gets its power for starting and for its fuel pump from the Coach 12-VDC batteries. So, of course, check that you have power from the batteries and that they are being charged by your Converter (which get's its power from the 110-VAC system.
If you put a multimeter across your battery terminals, it should read around 13.5 VDC if charged and around 14.5 VDC if it is being charged.
I suspect that this is your problem, but if the generator still does not start, or even "click" you will need to trace your 12-VDC to make sure it is present on the generator starter terminals themselves, and they are a little hard to get to.
Question: I'm new to RVing, and I have a brand new motorhome with an onboard gasoline generator. A helpful camper showed me the altitude adjustment when the city power went out in Albuquerque, and the generator would fire, but not stay on. When we got just about to Oklahoma, the generator turned off on me. I went to adjust the setting and discovered the generator cover was gone (that may explain at least one of the weird noises). Could I run the generator without the cover, or will that actually damage it?
Answer: Your generator can operate just fine without the cover. But, you need to get another one from the manufacturer because it is part of the noise baffling system and the noise will not just irritate yourself but your neighboring campers.
FYI: If your new RV has sat for a long period of time the fuel filter for the generator may be partially gummed up from sitting with fuel drying up in it.
I would look under the chassis where the RV generator is mounted, and you should see a fuel pump/filter combination there. Get the model number and purchase a new filter to see if this is why it isn't running properly.
Question: Why does my new generator in my RV not power anything? We have full power when plugged into electricity.
Answer: From our symptoms, I have to assume you have a motorhome with a built-in generator?
If this is the case then I also have to assume that the generator runs but your Rv does not switch over to it for 110-VAC power?
With these two conditions being true, then you should know that your motorhome has a "transfer switch' which is actually a solenoid that your power management panel used to select either the external power or the generator for power. Two AC power sources cannot be tied together so this transfer switch doe the job for you. When the power control panel senses that the generator is running and generating power, then it switches over to the generator as long as it is running.
So, check two things first;
1- is your Coach battery fully charged? If not, your Power Control panel will not operate properly. If the battery is OK, then you may either have a bad "power generator" portion of your generator, or
2- you could have a bad transfer switch. The transfer switch being bad is the most common cause of your problem.
Question: The power in the campground went out. Do I have to turn the electrical breaker switch off before starting the generator?
Answer: An RV with a built-in generator will automatically switch over to the generator when you start it, and back to shore power when it is turned off. This is a safety feature in motorhomes.
Question: why are our RV's TV and refrigerator not working when we are plugged into the electricity?
Answer: Without knowing what design RV you own, I can only guess at which systems yours uses.
So, Your TV's typically use receptacles that are powered by your INVERTER, so they will operate when you are Boondocking and don't have external electrical power. So check that the Inverter is operating.
2- Considering that your Inverter operates on your COACH battery, you should check that it is operating properly.
3- Your fridge should operate on 110-VAC when your RV is plugged into external power, BUT the fridge control circuit board operates on your COACh battery.
I would suggest that you check your Coach battery and that it is being charged properly by the RV Converter.
Question: I just bought a trailer and the AC, microwave, etc. won’t turn on when the trailer is on. I am a newbie. Am I missing something?
Answer: If you're plugged into a campsite power box, then check the following;
1- Did you turn the power box breakers to ON?
2- Is your power cord firmly plugged into the power box and your camper?
3- Is your trailer's MAIN power breaker turned to ON?
These are the three essentials a newbie might not check.
Question: Can I start my onboard generator without my RV running?
Answer: Yes, The onboard generator starts using your COACH battery. And, when it is running, the external power is switched OFF.
And it is common for some motorhome owners to run their roof air conditioners and some other equipment while they are driving on the highway.
Question: I have a diesel 8000 Onan pretty new coach 2017. Had issues on my last trip with the transfer switch which I got replaced. Just took a short trip and the generator keeps shutting off when I am driving. I had to turn it on several times, runs for a while then shuts off. What is odd is that when I got home I had it on for about an hour with both A/C’s on with no problems. Took a 15 min trip to sprays and it went off again. Do you think it could be the batteries? Oil level is good.
Answer: There is a safety feature designed into motorhomes that some people don't realize.
The motorhome manufacturers place the fuel line for the generator only down to the 1/4 tank mark. This restricts the driver from using up all of the engine's fuel while out Boondocking, and then not be able to get to a place for a refill.
So, first, you should check that you have enough fuel in your tank to run your generator and also drive.
If this is not your problem then you might want to change the fuel filter for your generator.
Question: Our generator is on but our microwave is not getting power. How can we connect the microwave to our RV's generator?
Answer: Your microwave, your AC units, your 110-VAC receptacles your Fridge, Ice-maker all operate on your external campsite external power normally. When you start your generator, your Power Control panel senses that it is ON and it switches your power over to the generator.
If the generator is running then you should check that your COACH batteries are fully charged and your CUT-OFF switch is ON.
If these conditions are met, then your Power Control panel should switch over to the generator, IF the battery is dead or has a very low charge then the Power Control panel will not operate properly.
Question: If I have no appliance battery in the RV but the ground for the circuit is plugged in; will it kill the vehicle?
Answer: Not a lot of information, but here goes;
1- What you call the appliance battery is normally referred to as the COACH battery. It is used only for the camper trailer or motorhome 12-VDC accessories and appliances.
2- The COACH battery on a motorhome (which I am guessing you are talking about) is not a part of the "vehicle" electrical system.
At the same time, if you have not been using your CUT-OFF switch to disconnect the engine battery when the motorhome is not in use, the electrical devices that operate on your engine battery, even when OFF will drain your engine battery.
Question: I have a 96 class a motorhome. I am new to roving there is black soot on the generator I took it to a nearby shop and had the generator exhaust pipe rehang with a new hanger. Do you think the black soot could have come from exhaust pipe being separated from the generator?
Answer: Back in the day before automobiles were computerized, it was common knowledge that 1- if your gasoline engine smoked and it was blue, then you were burning oil, and 2- if your engine smoked and it was black, it was "burning" gas.
Ans, if your generator exhaust was disconnected then, yes, the exhaust could be getting inside the generator housing.
Check the total hours on the generator before you start to get an indication that it may just be worn out or not and need replacement or an overhaul.
If it were me, I would have the generator 1-steam cleaned properly, 2- install new air filters, 3- change the engine oil, 4-install new fuel pump filter, and then have it "tuned up" by a generator mechanic.
The mechanic will be able to tell you if the generator can be fixed or not.
Question: I have a 2003 Itasca MH other 50 amp service. It has an onboard generator that works fine. Can I wire in a 220-volt outlet from the fuse panel to run a 220-volt clothes dryer?
Answer: Here are several things to check:
1. Most RV's are pre-wired and plumbed for a washer/dryer hookup. Check if yours is prewired
2. Your generator should typically be a 5K generator, and this would be enough power capacity for your washer/dryer.
3. You would need to add the appropriate breakers for a washer and a dryer.
4. Most RV's use a combination washer and dryer unit to save space, but I have seen some RV's where separate units were added.
5. Remember these appliances are heave and MUST be mounted so they will not bounce around and damage your RV's interior.
So, considering the things I have listed here, yes, you can add a Dryer hookup but make sure to do it safely.
Question: My motorhome has a diesel generator. Why does the generator operate off of the house batteries instead of the chassis batteries? It seems to me that weak house batteries will prevent a generator from starting up in extreme heat, forcing the air conditioners to operate. Is there a way to switch the wiring system from house to chassis?
Answer: The philosophy with motorhomes is that you should not have any superfluous appliances loading down your chassis battery. It is definitely not recommended that you "redesign" your RV wiring away from the standard configuration.
The standard system design you have works well, and the power control panel would not operate correctly if you change the high-current wiring.
Question: My RV onboard generator sometimes powers up the coach (microwaves/outlets) and sometimes it doesn't. It starts with no problem and transfer switch is fully functional and new. What could be the problem?
Answer: From what you have told me here, your generator is functioning and running properly but you do not have any AC power in your RV, at times.
If this is the case then you need to have a tech check out the "power generating" portion of your Generator. It sounds like there might be a problem there, or you could have a loose wiring from the generator to the RV power system.
Question: Does the Onan RV generator make its own power to run? It's in a 1998 Coachmen Catalina Class C Motorhome.
Answer: The Onan generator in any motorhome uses the COACH battery to start and then it actually operates on the RV's fuel system.
Question: I have a 2006 Conquest SE with an onboard generator. The generator starts and runs, but it does not seem to run anything. Is there a switch or something to make the appliances work?
Answer: Your microwave, your AC units, your 110-VAC receptacles, your Fridge, and Ice-maker all operate on your external campsite external power normally. When you start your generator, your Power Control panel senses that it is ON and it switches your power over to the generator.
If the generator is running, then you should check that your COACH batteries are fully charged and your CUT-OFF switch is ON.
If these conditions are met, then your Power Control panel should switch over to the generator, IF the battery is dead or has a very low charge, then the Power Control panel will not operate properly.
Check the battery.
Question: Our heater just stopped working. We just got this RV and drove it twice. It says the propane is full. It’s a 2015 Thor Axis 24.2. Any advice?
Answer: First of all, make sure your valve for the propane line is turned to "ON".
Then, check that your propane is working by turning on one of your stove burners.
Once these checks are run, then check that your COACH battery is fully charged because it's 12-VDC powers your temperature control panel.
Check if the temperature panel is operating by turning on your AC.
If everything operates OK, then your furnace itself is the likely culprit and needs to be checked by an RV tech.
Question: I have a 1997 Allegro Class A. When I turn the ignition switch to off the generator shuts off. What do I do to keep it running without the ignition switch on?
Answer: The generator does not use the engine power, and the ignition switch should not have any effect on its operation. So, I would check that the MAIN and AUX (12-VDC) switches are turned ON so that the generator can have 12-VDC to start and run. Otherwise, there is no reason for this to happen.
Question: will a 3,000-watt generator operate the A/C while parked?
Answer: The built-in generator of motorhomes, if it is a 3K or a 5k, are typically designed to provide adequate power for all of the internal 110-VAC equipment and accessories. Sometimes, the user can have too many appliances plugged into the RV receptacles and cause the main or one of the receptacle breakers to kick out.
Question: How many batteries are there in a 1985 Ford Tioga RV?
Answer: I don't have any specs on an RV that old (1985) but, typically these older Class-C motorhomes will have an engine battery and it will have another 12-VDC battery for the interior accessories and other equipment that operates on 12-VDC.
Having such a second battery takes any load and current draw off of the engine battery, so the Rv is always ready to start and go.
Question: I am new to using my generator to power my RV. If there is no shore power, do I plug the electric cord in the outside compartment into the receptacle in the same compartment? What is the outside receptacle for?
Answer: You should have an External Power cord that fits into the External Power Socket on the outside left rear of your RV. It is a special waterproof cable that is capable of handling either 30-Amp or 50-AMP power which is why it has the "strange-looking" connectors on each end.
Question: I changed the oil and filter on the generator in my motor coach and now the generator won’t start what could be the problem? It is a 33 0 diesel.
Answer: Changing the Oil/Filter on an RV's generator should not have any effect on it operating unless your oil level is low.
Many generators will have a sensor that detects if the oil level gets low and stops the generator from running to protect it from damage.
But, if you have adequate oil in the generator, this shouldn't be the problem.
So, check your oil level.
Question: What kind of oil do I put in my RV generator?
Answer: Read the generator owner's manual and it will list the acceptable products to use. Typically the recommended oils for most generators are similar to auto engine oils, but I would check what is recommended for my specific brand and model.
Question: I have a 1976 Chevy G-30 1-ton Marathon motorhome. Where are the generator and the turn-on switch located?
Answer: The simplest way to find your generator is to look for the 1-inch diameter exhaust pipe and trace back to the generator itself.
There will be an On/Off/Start switch on the dash of your motorhome and on the generator itself.
Question: My RV generator is running, but only the microwave is powering up! What do you think is the problem?
Answer: First of all, is your COACH shut-off switch turned ON? It runs on 110-VAC like the microwave.
Secondly, is your converter (charger) keeping your COACH batteries charged? Check the voltage on the terminals of the Coach batteries.
Question: A few minutes after turning on our Onan Generator on our class C rig, it smelled like it was burning. What do you think the problem could be?
Answer: Pull the covers off of the generator and inspect it for road debris. Then, examine the generator exhaust pipe for road debris. If everything is OK, then you need to get that generator to a service center.
Question: Why would a carburetor be a problem on a brand new Class C RV? The dealer is refusing to fix it under extended warranty, and blames us for not using it enough.
Answer: First of all, a warranty is a warranty and they typically only have an end date or mileage limit. And I suspect that if you read yours, it will not say anything about how much you use your RV.
Most newer RV's will utilize a fuel injection system rather than an old-fashioned carburetor, but whichever you have the Rv will have at least one fuel filter.
These fuel filters are what will "gum-up" if they sit and the engine is not run regularly. Most people will run their Rv engine for 20 minutes or so every month just to avoid this kind of problem. So I would MAKE the dealer check the fuel filter.
But if it is gummed up, that would be an expense of yours. As it is an expendable part.
Question: A red lighting is blinking inside my motorhome generator. What does that mean?
Answer: The ONAN generators utilize this red light and the number of blinks to provide the owner with a few error codes. These error codes should be listed in your generator owner's manual. If not, you can find digital copies of the manual on the web.
Question: why do the gfci plugs only work when the converter is turned off when using our generator?
Answer: Your GFCI receptacles get their 110-VAC from the MASTER GFCI receptacle. It, in turn, gets its 110-VAC from your AC-Power breaker panel, just like all of your other 110-VAC receptacles do.
Your Converter is simply a charger, plugged into a receptacle, that keeps your COACH battery charged.
Your RV normally gets its power from the external power cord or from the generator and this is sensed and switched using the input Transfer switch.
The AC Power breaker box does not power the Converter separately.
But, if your COACH battery is BAD then the battery will not be charged, and many of your 12-VDC devices in your RV will not operate properly, such as; interior lights, temperature control panel, power management control panel, alarms, and more.
But, there is no connection between the Converter and the GFCI receptacle!
Question: I need to wire up my shore power and generator power for my outlets and air conditioner to work. In the generator outlet box, I have the generator plug wired in and it is receiving 122 volts. There are two additional sets of wires coming from the top of the mental outlet box (two orange wires = 6 wires). How do I connect these wires to the generator plug in order for the coach and shore power to get power from the generator?
Answer: First of all, your AC units in your RV operate on 220-VAC. Your external power cable uses 4-wires; two are separate 110-VAC sources, one is your COMMON wire and one is your GROUND wire.
Without any more information on your situation, that's pretty much all I can tell you.
BUT ---- Make sure your generator is capable of generating two different 110-VAC outputs, and then make sure that you wire the COMMON to COMMON and the GROUND to GROUND and you don't mix things up.
AND, I m assuming you have an RV that is already wired with a TRANSFER Switch system that will select between the Shore and Gen power systems? They must be kept isolated from each other with this kind if Power Transfer switch.
Question: I have a 1999 Coachman Class A with an Onan 7000. My problem is that the generator will not change the coach batteries. Any thoughts?
Answer: Your motorhome has a Converter that charges your COACH batteries, and it is powered by your 110-VAC regardless of whether you are running on your external power or your generator.
Check that you do have power out of the generator to other 110-VAC appliances and that all of your breakers are reset.
Question: My generator won't turn over, I just installed 2 new coach batteries. The breaker for the inverter/ converter won't reset. I was wondering if this non-resetting breaker could be a problem when trying to start the generator?
Answer: Some companies do make a unit that is a combination Inverter and Converter, but this is not common and they are separate units.
Neither the Inverter or Converter are used to start your RVs generator. The COACH batteries are used for starting your generator. So, it sounds like you have two problems.
I suggest that you go back and recheck the wiring to your COACH batteries and make sure you have everything wired properly. Your Converter is used to keep your COACH batteries charged and your Inverter will use your 12-VDC from your COACH batteries to power a few receptacles that you use for your TVs and maybe for a computer while you are traveling.
Considering all of this, your symptoms suggest that you have not rewired the new batteries properly, so again, make sure that you have things hooked up properly.
Question: I have 2004 Fleetwood Discovery with a diesel 7500 generator. While running it shows 13 amps being used but the only device on is the fridge. Not sure what else is making the amp draw. Can you help?
Answer: Your converter would be running and keeping your 12-VDC COACH batteries charged. So, are these batteries in good condition and do they have water in them? Many motorhome owners will forget to maintain their batteries.
This is also a common problem on motorhomes which have batteries that have aged. I recommend that you check this first.
Question: We have a 2017 Thor Chateau 24. On a trip, a pipe hanging underneath the RV that exits near the driver’s door dropped down. It elbowed up toward the engine. I removed the hangers and the pipe. The engine light was also on prior to me finding the pipe problem. Is this a generator exhaust or something else?
Answer: A generator exhaust pipe is typically a 1-inch diameter pipe while the engine exhaust would be much larger, so let's assume the pipe goes to your generator.
Other than that, your engine light being on can be an indicator of something simple most of the time. But, you need to get that checked as soon as possible.
Question: I have a 10kw Onan that has been working great, it's maintenance is up to date, but all of a sudden it won't run more than 10-15 seconds at a time. I have traced the problem to a fault code that says it's due to overvoltage. I've tried to do a reset, but have not had any luck. Is there a part that needs to be changed or does the code need to be reset by a technician?
Answer: Your trouble code is indicating that the generator itself is putting out a voltage that's too high.
Hopefully, resetting the generators controller will fix your problem, otherwise, you could have a regulator problem in the generator itself.
Question: I am new to all of this RV stuff. To use my generator to power my RV ( if there is no shore power), do I plug the electric cord in the outside compartment into the receptacle in the same compartment? What is that receptacle for?
Answer: From your symptoms, I assume that you have a travel trailer or a Fiver? and want to use an external generator for power? You would plug your external power cord into your RV's external power receptacle. It will be a 30-Amp or 50-Amp power cord, so it will be waterproof and have a special connector on one end that mates with the external power connector of your RV. The other end of your external power cord would connect to your generator, IF the generator does not have the appropriate matching connector, you will need for an electrician to wire the appropriate connector on your generator.
Question: I had to pull my Onan generator out of the RV to replace the fuel pump. Can I test run it without putting it back in the camper?
Answer: To Your Question; As long as you have it mounted on something like a table, it should run properly. you did not mention your Rv model, but with most ONAN generators ib RVs, you can change the fuel pump by crawling under the RV at the generator and the fuel pump is mounted directly under the generator. Just follow the fuel line from the fuel tank.
Anyway, to our question, you should be able to test your generator the way you asked.
Question: The inside panel of my RV does not have a chocker position for my generator. The outside generator shows off and choke on the same switch. Do I push the off switch on the inside panel for a choke?
Answer: On most generators used in motorhomes, there is no manual choke. It will have an automatic choke.
The switch is actually just an ON - OFF switch that you can hold for a few seconds to get it to start.
That's all I can say about your problem with what you have told me.
© 2010 Don Bobbitt
Don Bobbitt (author) from Ruskin Florida on August 24, 2020:
David - That gauge indicates the number of hours the generator has run. So, whenever you get it serviced, write down the reading on the gauge and then write down the hours it should indicate when you need to service it next.
David Miller on August 24, 2020:
2019 Thor ACE generator gauge shows number of hours. Does this mean number of hours to run until 1/4 tank or number of hours used?
I think number of hours to run. I have not used the generator that much so do not think it mean used hours.
Don Bobbitt (author) from Ruskin Florida on August 19, 2020:
Dean - This is the number one problem with RV generators. You must keep the inline fuel filter clean and your fuel pump must be kept in good shape. So, replace the fuel filter, get rid of that trash in the fuel bowl, and you may also need to replace the fuel pump itself.
Dean johnson on August 19, 2020:
I have a 1976 RV Camper and my generator wont stay running . so i checked carberator there was fuel on top but the sediment boul was completly dry .i also pulled the fuel pump and i cant brrath through could the fuel pump be plugged . the camper did dit a few years with gas in it
Don Bobbitt (author) from Ruskin Florida on July 09, 2020:
Sharae - From your symptoms, it sounds like your brother added the connection for your Rv to the same breaker as his dryer. He needs to add a specail pair of breakers to is breaker panel, just for your RV to handle the extra load when you are using your high current devices such as your RV-Air Conditioner.
Have a Nice Day,
Sharae M on July 08, 2020:
We are hooked up to my brothers electric outlet on their house and everytime we try to turn the air conditioner on it blows the breaker to their wash room and the RV. Can you tell me what i need to do please and thank You.
Don Bobbitt (author) from Ruskin Florida on July 08, 2020:
RON - the Plug could be either straight blade connections or twist-lock connectors.
Your RV external power cable must, of course, match the female receptacle of your external generator. the same as it does the one in your campsite power box
Typically you will have 220-VAC service at either 30--AMPS or 50-AMPS..Either will use t separate 110-VAC pins, one Ground Pin and one COMMON pin.
Have a Great day,
Ron Gallion on July 07, 2020:
If at an electrical site. What configuration is the elctrical plug
Don Bobbitt (author) from Ruskin Florida on June 24, 2020:
Julie - That charge has to be wrong. Unless they are providing you with the gasoline for the generator, even then that's high.
You should figure that a typical 5kW generator will usually burn about 1.5-2-gallons of gas an hour,
So their generator fee means over an 8-hour night, you would only use maybe 15-gallons of gas, but you would b charged 8x40 or $320 per night for using their generator???
It seems that their fee, if you are using your own gas is for "wear and tear" of the generator but, Well, WOW!
I hope you find another solution.
Julie on June 24, 2020:
I am considering an August RV rental. There is a $40/hr charge for running the generator. If I rent for a few weeks and run it overnight that would be lots of $$$. But it’s summer and I imagine I’ll need to do that to keep us cool in there?
Don Bobbitt (author) from Ruskin Florida on June 15, 2020:
Mike - An RV owner is always tinkering with something on his RV. That way, he finds potential problems before they occur.
Have A Great Day,
Mike on June 15, 2020:
Thanks so much Don for this very informative post. Packed with info and a reminder that a generator shouldn’t be taken for granted and needs some TLC.
Don Bobbitt (author) from Ruskin Florida on May 19, 2020:
Your COACH batteries are charged by your Converter, and it runs on 110-VAC, regardless of whether you are running your motorhome on external power or your generator. So, I would recommend that you check that your generator is powering your internal appliances.
Jim Loeppky on May 18, 2020:
Thanks for all of your help. My problem is, my generator does not charge my coach batteries. 1999 Coachman. Onan 7000. Any thoughts?
Don Bobbitt (author) from Ruskin Florida on December 18, 2019:
John - This kind of project can be a little tough at times, but with perseverance, I suspect you will end up with your portable generator at some time.
Have a Great Day,
John on December 18, 2019:
Thanks. Still not sure of type, haven't looked at it in a while. Am hoping to have someone with more electrical knowledge than I tackle it. Haven't been able to talk one into helping me out so searching for input. Duh, wiring diagram, ha, I shall seek this info. Dropped it and covered it, to dang heavy to move by myself, it's getting wheels. Thanks again
Don Bobbitt (author) from Ruskin Florida on December 17, 2019:
This could turn into a bit of a task if you do not have any electrical skills or training.
But one thing you can do is contact the manufacturer and ask for any electrical diagrams of their standard non-RV generators of the same model. You didn't mention the name but ONAN makes many of the RV generators.
Again, the mechanical modifications and then the electrical wiring will require a lot of work if you are going to end up with a safe project.
John on December 16, 2019:
I got a 7kw generator removed from a motorhome, motor home was scraped. Now I want to make it probable. Now I'll need an external fuel tank and battery but haven't a clue how to add outlets to make it like a factory portable unit... Can you help
Don Bobbitt (author) from Ruskin Florida on November 09, 2019:
Rod - No, your generator is not designed to shutdown after a period of times. It will run for days if all is OK!
I would check my COACH battery to make sure it is not an old one and that it has water in it. If these things are OK, then your Converter should keep your battery charged. If the battery voltage drops very low then several things can happen but the most common is that your power control panel could malfunction. Also, I should ask, how long has it been since you changed out your fuel filter to the generator, these are cheap and can "gum up" after sitting for a while.
Rod Sredwos on November 08, 2019:
Don, great article. Thanks for posting. I recently acquired a 2014 39' Winnebago and am looking to use it in cold weather the next couple of weeks in the midwest for football game tailgating before I put it away. My generator runs fine but automatically shuts off after some period of time. My question is...does it do that when the coach batteries are fully charged? I can't find anything in the manual about an auto-shutoff so I am curious why it would shut off.
Don Bobbitt (author) from Ruskin Florida on November 04, 2019:
George - This built-in safety feature can be a nuisance for RV traveler, especially if you do a lot of off-road camping. But I'm glad you read my warning and took care of the problem.
Because of this little feature, when I am traveling, when the gas gauge in my motorhome drops below 1/2 tank, I will often start looking for a gas station, just to be sure I always have enough fuel.
I'm glad my articles were of some help.
Have a Great Day,
george scully on November 03, 2019:
I was running my generator for awhile to just keep it in good shape when it stopped. primed it & cranked it. no start. Then disconnected the fuel line, primed & cranked it , nothing. I suspected the main tank needs to be above 1/4 full. It was not. Read your article to reconfirm my thoughts. I'll get some fuel as this seems to be the problem. Thanks, George
Don Bobbitt (author) from Ruskin Florida on October 24, 2019:
Probably the first thing you should do is make sure your COACH battery is fully charged. The reason is that it provides the 12-VDC that your Power Control Panel uses to sense and control your AC-Voltage systems.
Your Power Control system senses when your generator is running and producing power, and then it powers your TRANSFER Switch that switches your RV AC systems over to the generator from the external power source. This switch is a high current solenoid that can go bad and need to be replaced.
Your symptoms indicate one of these could be your problem; either the Transfer switch solenoid, or your COACH battery voltage being discharged.
Gritty Eileen on October 23, 2019:
Thanks for the information. Quite helpful. I have a 1995 Europa MH with a built in Generac 4500watts. Generac no longer makes RV generators. Parts availability are dwindling. The generator powers up but there is no power to the MH. How to pinpoint the problem in order to see if it can be repaired?
Don Bobbitt (author) from Ruskin Florida on October 15, 2019:
Sam Royder - You'll find that a propane generator is surprisingly similar to a gas one. The major differences you will see will be at the fuel input and management system. The rest of the generators are the same.
Have Nice day,
Sam Royder on October 13, 2019:
Thanks for the info on gas and diesel generators. Can you provide any maintenance or repair info on propane generators. I have a 2500 Onan that operates on propane.
Don Bobbitt (author) from Ruskin Florida on September 24, 2019:
Jeff - The generator should already be receiving its fuel from the regular RV fuel tank.
I am not aware of any "return line"? in a motorhome.
Jeff on September 23, 2019:
have class b motor home 1995 chevy 30 coachman with 2800 Onan generator
can the vechile return line be used to supply generator
Don Bobbitt (author) from Ruskin Florida on September 03, 2019:
Motorhomes have a safety design to protect the owner from running out of gas.
They only put the fuel hose for the generator down into the gas tank to the 1/4-full line.
This allows the owner to have enough gas to get back to civilization when they have been "dry camping".
Try adding gas to the tank.
Have a Nice Day,
shari on September 03, 2019:
my generator won't turn on. I took the gas hose loose and there is no fuel going through the hose. what should I do to fix this problem
Lisa ARA on August 22, 2019:
Don Bobbitt (author) from Ruskin Florida on August 22, 2019:
Lisa - Thanks for the response. So, your generator runs and starts, so your core problems is that you have no output voltage from it.
And I can say, with some confidence that your RV electrical system itself is not involved in your not getting power from the generator.
You may have to bite the bullet and call that manufacturers customer service number 1 (888) 436-3722) for help and if they can't help you, then look for a reliable generator technician nearby.
You could try going to the RV owners site called IRV2. They are a group of campers who own Rvs and they help each other out with problems that pop up. I recommend that you check with them.
Sorry but that's the best I can do for you remotely and not having worked on a Generac before myself.
Lisa ARA on August 21, 2019:
Yes, the generator was factory installed.
Yes, the generator is running. There is one glass fuse that tests fine.
You stated to check if there is 13.5 or higher VDC to the starter terminal. Is this any relation to "starting" up the generator? Or a separate funtion?
I've been combing the internet trying to find a service manual for this model (02010) to pinpoint said test points....etc.
Any ideas are welcomed!
Don Bobbitt (author) from Ruskin Florida on August 21, 2019:
First, I need a little more information. Is this generator factory installed in your RV? Or was it added?
If this is a factory installed generator, then it gets its power to start from your RVs COACH battery. So, I am assuming your generator is starting and running, but you have NO AC-voltage at its output?
Considering you say everything works properly when you are on Shore Power, but you have no voltage at the generator's output pins (2-wires with 110-VAC on each each when referenced to COMMON, then the generator has a problem. Check the generator for any fuses it may have on its body somewhere, and check that you have a good 13.5-VDC or higher to the generator's starter terminal from your COACH battery.
Lisa ARA on August 21, 2019:
I have a Generac Primepact 50G generator that has no AC power going to the 30 AMP plug in the next compartment.. I have flipped all internal coach breakers. When plugged into shore power all is well. I placed a meter in the 30 AMP outlet and got zero volts. Tracing the power cable from the outlet to the generator, it arrives at two separate breaker switches (20 AMP and 30 AMP). The 2 neutral wires and gnd from the same cable are tied to a common ground bolt.
There is a Voltage Regulator module (F9719) that has a RED Led that never lights up. There is also a Control Board (9931 printed on the side).
What do I need to check for? I figured it may be one of these two modules, and probably the RED LED does light during some point.
How should I proceed?
Don Bobbitt (author) from Ruskin Florida on August 19, 2019:
Johnny, You have not given me very much information about your RV, but generally speaking, in a motorhome, the generator uses the battery to start and while running it should power your Converter which in turn keeps your battery charged.
So, check that your battery is OK, and can be charged?????
Johnny on August 16, 2019:
My generator runs fine but my battery runs low thrn my generator stops running
Don Bobbitt (author) from Ruskin Florida on August 15, 2019:
Becky Wachtman - Your generator starts using the COACH (Aux) battery. And once it is running, it provides AC-Voltage for your Converter which keeps your COACH battery charged.
The only time your Engine (MAIN) battery is involved with the generator is when you use that (AUX) rocker switch to temporarily tie the two DC-Voltage systems together when the COACH battery is too discharged to crank the generator.
Remember when you are dry camping you are using that COACH battery for all of your interior 12-VDC accessories.
From your symptoms, I suggest that your COACH battery may be getting old, or it maybe low on water, because it seems that it does not have enough power to start your generator after a night of dry camping.
Have a Nice Day,
Becky Wachtman on August 14, 2019:
I understand our generator needs to pull from the chassis battery to start. It appears to be charging the house batteries fine! But it also appears to be draining the chassis battery as it runs. Its an onan generator in a fleetwoid tioga class c. When dry camping, the first couple of times we start the generator, it starts fine. But the 4th or 5th time it cranks and wont start. If we hold down the rocker switch, we can get it to start from the house batteries OR if we start the engine first, then we can start the generator. What are we doing wrong?
Don Bobbitt (author) from Ruskin Florida on July 28, 2019:
Ideally, you always want your RV to be leveled. The generator and the Fridge are relatively forgiving, but they do call for level conditions within 3-5 degrees to function properly.
Have a nice day,
Karen Waring on July 28, 2019:
I have a Class C RV Four Winds Chateau. Do i need to be level for my generator to work right ?
Don Bobbitt (author) from Ruskin Florida on July 24, 2019:
MIlesnorth - RV electrical systems are confusing to many people who are not trained or at least used to them.
I fear that your main problem may be the fact that your RV is a customization of a commercial bus into a motorhome.
I say this because there is no way for us to know if the one who customized the electrical systems attempted to make their "new motorhome" function the same as standard ones do?
I do recommend that you try to make yours as close to these standard configuration as possible if you are going to drive it. But if you are essentially building a "house" that will never move, then you can more easily follow defined house wiring standards, even for how to wire a backup generator.
As to looking at pictures of pieces of equipment? I actually recommend that you post these on my electrical troubleshooting article for others to see, as well as myself to help, with identifying.
And, I recommend that you join the site IRV2. This is a group for RV owners who help each other with problems.
Milesnorth on July 23, 2019:
Hi, I am trying to figure out the systems in a 42 ft bus converted into a RV. We are at a bit of a loss as to where to start actually. I wondered if I might be able to send some pics of the systems for some help identifying them (and how they work together). I am located in Chugiak, Alaska, and I haven't had alot of luck finding anyone up here to assist in the adventure. You look like you know your stuff. If you would be willing to look at some pics and offer some advice, that would be fabulous!
Don Bobbitt (author) from Ruskin Florida on May 23, 2019:
Lois - Your symptoms are a little confusing, but I am assuming that you have a motorhome with a built-in ONAN generator???
If this is so, then using it as a power source for a few appliances, assuming that you used your RV's electrical receptacles, should not have damaged the generator at all.
One thing you can check though is if your COACH battery is still OK, in that it should have water in it and have a full charge on it because it is used to start your generator.
PS. Remember that your generator will not get gas if your fuel tank is below 1/4 full.
Lois on May 22, 2019:
We ran our Onan generator without turning the engine(gas) on when we lost power in our house. We connected our main appliances to it. Now the generator won’t run. Did we make a big mistake. Just bought the generator last year.
Don Bobbitt (author) from Ruskin Florida on March 15, 2019:
First of all, your Ford Brougham has one battery for the engine, and depending on the year, it can have one or two batteries for the HOUSE (or COACH) equipment.
The two generator start switches are there to give the operator the option of starting the generator from either spot.
The generator has its own fuel pump, normally mounted near or under the generator itself.
The fuel pump/fuel filter combination are two pieces that you will find in the fuel line and the filter must be clean and the fuel pump is powered when the generator start switch is pushed.
A dirty fuel filter is the most common problem for an RV's generator, with a bad fuel pump being second.
I would change both out.
Tracy on March 14, 2019:
Hi Don I got a 1984 Ford Brougham.
I can get the generator to run I just can't find a switch to flip the fuel pump on it's not getting gas and there's no obvious switch other than the generator start switchs. One on the unit one in the coach also trying to figure out where a wire goes underneath on the house batteries and I just found two more house batteries.
I'm stumped I need this gen to start
Don Bobbitt (author) from Ruskin Florida on March 12, 2019:
Rebecca - Considering the age of your Bounder and its past service history, this is likely buildup in some of the oil lines and particularly in the oil pan.
And I am assuming that your engine is not smoking and there is no heavy black buildup in your exhaust pipe. If there is buildup at the exhaust pipe you may be actually burning oil which can often be caused by worn piston rings.
I would hope for the best and check with your local Ford truck service center and have them check the engine out for you.
Rebecca on March 12, 2019:
My 1988 bounders, oil is still runing black after new oil change , do you know what is causing this?
Don Bobbitt (author) from Ruskin Florida on January 02, 2019:
Vidhan - You are absolutely right, there are a number of small portable generators that are quite adequate for the load a smaller camper will be.
And, the size of the load a larger camper like a motorhome provides requires a generator that is hard to haul around, thus the reason so many have generators that are built-in.
In fact, because of the smaller electrial load, there are several companies who make Solar Panel kits that can be installed in a Pop-Up or small towable trailer camper. They work well with an Inverter and there is not gas purchase required.
CHeck these out for a viable power option, especially when you are out boondocking.
Have a Great Day!
Vidhan on January 01, 2019:
Towables like small travel trailers, teardrop trailers, fiberglass eggs and even many pop up campers can be operated on a less expensive portable generator.
Don Bobbitt (author) from Ruskin Florida on December 02, 2018:
Mark - I am not familiar with that particular external generator, but if it is only putting out such a low voltage then you will need to get it checked by a service shop. It may have internal problems that a user should not try to fix.
Mark on December 01, 2018:
I have a general 110 voltage generator that’s only putting up 48 V what is the problem
Don Bobbitt (author) from Ruskin Florida on November 05, 2018:
truth2ak - Yes, I'm afraid so.
But, in most motorhomes you will have a couple of receptacles that will be pwered by your Coach batteries via an INVERTER which uses the 12-VDC to generate a limited amout of 110-VAC.
These receptacles exist normally to provide power for your TV sets and often for a computer receptacle near the passenger seat.
Have a nice day!
truth2ak on November 04, 2018:
When driving do you have to run the generator to run the appliances and outlets?
Don Bobbitt (author) from Ruskin Florida on September 01, 2018:
Lennie - Your Bounder is wired so that you can use it, even while on the road, for your roof AC's and other equipment.
Your '96 will only have a 30-Amp service standard, so I would only run one of the AC units to avoid any problems with overloading the generator.
FYI: Your RV has a power control panel which does several things allocating power to equipment, but most importantly it switches to the generator when it senses that there is a generator running.
So, while sitting in your campground, plugged into campsite power, see if you can start your generator? Your Rv should sense it is running and switch the "transfer switch" over to the generator. If it switches over, then this function is working so you can then turn your Air ON. IF it runs OK, then your switching system is OK. If it doesn't run, then you are overloading your generator and you need to check it out.
Bing new to you, I would suggest that you do the following to your used generator anyway; 1- change the generator oil and oil filter, change the fuel pump and fuel filter, and change the air filter.
If it still doesn't take the load, you may need to get a generator tech to check it out for you; you can usually contact the generator manufacturer's customer service and ask them for the nearest certified tech.
Being a Rv traveler for many years, I do suggest that you keep your generator serviced and in tip top condition.
So, check the things I mentioned and have a great time with your new/used Bounder.
Lennie on August 31, 2018:
I jis bought a 96 fleetwood bounder self contained with a 5000 onan generator and we cant figure out for the life of us, how to run the roof airs while going down the road, idk if we are not turning on the right switches on the main battery/and the other battery on the wall inside the rv, or if we are suppose to have it on 20 or 30 amp on the generator, but we cant get either air to come on while driving, but if plugged in at a camp, it will.....any ideas?
karen on March 27, 2018:
Useful and informative. Thanks
Don Bobbitt (author) from Ruskin Florida on March 24, 2018:
Phyllis Waltman - First of all, an RV with a builtin generator also has an automatic switching power controller so that you can only have one thing providing power to your generator.
So, to use your external generator you will need to be the proper adapter cables so that you can plug your RV into the generator when you need power while boondocking or camping anywhere other than a campground.
But, check your RV to see if it has a builtin charger (Converter) that will use the ACV from the generator (or campsite) to recharge the Rv batteries.
Here are some tips for you if you are going to use a generator, built in or external.
1- campgrounds do not allow generators at all or some few will allow their use up to a certain time at night.
2- Many Walmart stores allow RVers to camp in their parking lots for a day or two, but only if they comply with their rules. There is a Walmart group on yahoo called walmartrving, or something like that. Check it out.
3- Some cities, towns and counties do not allow overnight camping anywhere, but many do allow it in some places. Many people will overnight in church and large shopping center parking lots, but you must check the local laws.
4- I recommend that you get some one to expand your RV battery capacity, and keep them charged. Many people will run their RV on the batteries while cooking or watching TV (you can add a cheap Inverter that will convert 12-VDC to enough 110-VAC for one TV). They then just recharge the RV batteries the next day.
Phyllis Waltman on March 23, 2018:
Our son offered us his generator he used at his house to camp with our 5th wheel. My husband said you have to buy a special generator just for rvs. We did not buy an rv with a generator and in traveling can not stay free anywhere overnight. We we are on a low budget so I am anxious to hear what you tell me.
Don Bobbitt (author) from Ruskin Florida on March 19, 2018:
Michael - First of ll, your RV batterie will only lat a few days with the load of a fan and a TV before they ill need charging.
(PS What about the fridge, it uses 12-VDC??).
Check and make sure the batteries are being charged when the generator i running, by measuring the voltage across the battery terminals. When being charged the voltage should be around 14.5 VDC, if it is 13.2 or loser it isn't being charged.
It they ae being charged, then you only need to charge it occasionally.
You might want to pick up a cheap solar charger for the RV to simplify your problem.
Good luck, DON
Michael on March 18, 2018:
I am a total newbee to the RV world, so please bear with me. I have a 5th wheel parked on a remote spot on my property. My partner's adult son is living in it. We anticipate that he will only be using power for lights, LPG heater fans and possibly tv. Would the 12 volt batteries suffice if they are periodically charged by the LPG Onan generator that is currently in the trailer? If so, for how long would it need to be charged? Also, I have a deep auto battery charger that I typically use by plugging into an outlet in my garage. Could this be used to charge the trailer batteries (by toting the batteries back and forth from the remote area to the garage)? I appreciate your tips.
Don Bobbitt (author) from Ruskin Florida on March 15, 2018:
pbtwins - Yes, your Rv is designed for your Gen. to be your major power source, and your RV does not need to be operating. Also, when you turn your generator ON, your RV power control panel will automatically switch everything OFF of your campground (or external) power.
Have a great day,
pbtwins on March 14, 2018:
Great article! I am a newbie and my question is do you turn the engine off when you use the generator? how does that work? we have a 1993 fleetwood flair class a Thanks!
Don Bobbitt (author) from Ruskin Florida on February 19, 2018:
Elizabeth - Standard clothes dryer, water heaters and electric Furnaces will typically require 220-VAC to handle the high currents required.
On the other hand, if you used a solar-assisted water heater and maybe a propane furnace the current needed would be significantly less. Of course if you're talking about a motorhome you have to use what fits their designs.
Elizabeth on February 18, 2018:
I was wondering, since you seem to know a lot about generators, if I were to use a generator for heating water, a washer and dryers and for heating, what kind of voltage should my generator have?
Don Bobbitt (author) from Ruskin Florida on January 26, 2018:
Diana - First of all, an RV with a built-in generator is usually designed to handle the full load of power that the specific RV might demand. Secondly, it is wired into the RV so that is is safe to use, as well as being set up to "kick out" if there are any kind of wiring problems. So, trying to use a larger capacity generator is not recommended without having a certified electrician wiring it properly.
Diana on January 25, 2018:
Hi,,, We are renting an RV (2016 Coachmen Leprechaun) and we were wondering if we could plug in our generator instead of using the generator that the rv comes with?
Don Bobbitt (author) from Ruskin Florida on November 29, 2017:
Steve - Sorry, but you said it yourself; the life of a diesel generator is dependent on how well it is maintained. I have seen people in 20 year old diesel RV's whose generators are still running great, and I've seen some getting major repair after only a couple of thousand hours of run time. There are just too many variables involved. One thing I would suggest is for you to pull out the generator manufacturers owner manual and read how far out it projects their maintenance schedule?? Sorry again.
Steve Kass on November 28, 2017:
Hi Don, I am looking into buying a used DP. I was wondering how many hours of run time on the diesel generator is too many. I can assume it will depend on how it was maintained. But can you ball park it for me.
Don Bobbitt (author) from Ruskin Florida on September 17, 2017:
Jim - our RV system is designed to do this. When your generator is running then it will not allow your external power source to be accessed. If there were two sources on the same appliances, etc, there would be some serious electrical damage in your RV.
jim vestergaard on September 15, 2017:
my generator cut my house power to my rv for a few hours when i run the generator
Don Bobbitt (author) from Ruskin Florida on August 21, 2017:
Dave Gutman - All gas powered Onan generators I know of are cut OFF by removing the 12-VDC from the fuel pump. I would change the fuel filter and the fuel pump. They are relatively cheap and easy to replace.
dave gutman on August 20, 2017:
i have class c forrester 2004 onan 4000 microquiet 2 questions
my generator cuts out after 2 hrs with load
all fuel is good tank full , fuel pump flow is good, starts up again but constantly dies that
secondly does the generator use 12v feedback in any way outside of starting , it cut out and realized my battery connection were loose ..
Don Bobbitt (author) from Ruskin Florida on July 23, 2017:
Mark Deerhelm - Running your generator regularly, such as once a month IS a good idea. The reason is that over time the gas (and additives) in your fuel will evaporate and leave a residue that can "gum up" the fuel filter or fuel pump, or some of the parts in the carburator itself. by doing this, you keep everything cleaned out and ready to run efficiently.
And, running the generator, if it's wired up properly, will not harm anything in your RV.
Mark Deerheim on July 22, 2017:
Don, I have a generator in my toy hauler. I've been told that I should run it once every month. I'm hooked up to power. Does it hurt anything to start the generator while I'm hooked? Thanks
Don Bobbitt (author) from Ruskin Florida on July 03, 2017:
Kathie - This looks like the classic case of a bad fuel filter or fuel pump. Read my hub on How to replace your fuel filter and fuel pump. It's actually a simple process that a person with a little maintenance skill can perform. Click on the link here;
Good Luck, DON
Kathie on July 02, 2017:
We have a diesel Winnebago Vectra 2004 with an Onan generator. When the generator is turned on, it runs for 5 minutes then quits. Do you have any idea why it might be doing this?
Don Bobbitt (author) from Ruskin Florida on June 28, 2017:
Rex - If your Tropi-Ca was originally wired for a generator, then you should be able to run the AC off of the generator as you travel. This has been a common way to keep your coach cool when traveling in very hot climates with motorhomes for decades.
So, hook it all up and run your own test.
Rex on June 27, 2017:
I'm restoring a 1997 National Tropi-cal with a generac 55k built in generator. Almost done and about to do an 18 state coast to coast tour. The a/c from the engine works well now. But this thing is 36 feet long and the rest of the coach ain't so cool. I'd like to run aux zone a/c off the generator while trucking down the road for comfort of others. Is that an option or is there another way. My first motorhome. I'm ignorant.
Don Bobbitt (author) from Ruskin Florida on June 14, 2017:
Susan - First of all, almost all campgrounds do not allow generators to be used. They generate exhaust fumes and they're noisy.
Second, I have had several motorhomes with a 5K-Onan generator, and with a half-load on the generator, it will burn around 1/3-to-1/2 of a gallon an hour.
Whenever we dry-camp, my wife and I fall into a routine where we only run our generator in the morning, and then for preparing dinner, and finally at night when we are relaxing, maybe with a little TV, before bedtime.
Susan on June 13, 2017:
We are wondering how much gasoline a generator uses if we ran it overnight if we were dry camping. And if it is more economical to dry camp in a campground or to use electricity provided. Do we save money getting a site with no electricity rather that one that does.
Don Bobbitt (author) from Ruskin Florida on June 02, 2017:
Jamie - The newer RV's have conventional fridge units the same as in your home. But most use a 2-way fridge that operates either on 110-VAC or on propane. If you have one of these in your RV, then you'll be OK. If not, I can only recommend the purchase of a very large, high-quality cooler filled with ice.
Don Bobbitt (author) from Ruskin Florida on June 02, 2017:
SUZY - RV Resorts and Campgrounds will almost all provide power hookup for your RV. In fact with these campgrounds, they do not allow you to run a generator except under specific conditions.
RV's have generators for use under tow conditions; 1- rough camping in wilderness conditions, or 2- when you stop in a rest area or truck stop and need power while you cook or sleep.
Some motorhome owners will run their generator while driving if the outside weather is so HOT that the dash AC cannot keep the RV interior cool. Otherwise, you shouldn't be using your RV generator very much at all.
Have a nice trip,
Jamie on June 01, 2017:
Okay so at the risk of sounding completely ditzy. ... is there something I can buy or whatever so I don't have to run my generator the whole time I'm camping?(I just bought one from Walmart online) I'm going to a festival and we can only run the generator an hour at a time but I need the fridge going as I'm festi mom this year and camping for friends and passers-by. . Also awesome article
Suzy on June 01, 2017:
Hello, im about to rent an RV and travel from Texas to Nevada and plan to stay at several RV camps and resorts therefore will I be needing the generator alot.. I ask because they charge us an hourly usage of generator. Thank you in advance we are new to RV world.
Don Bobbitt (author) from Ruskin Florida on May 29, 2017:
Leonard Jauquez - Your generator is designed to; 1- keep your house batteries charged, and allow you to operate in a state park or out in the wilds where there is no power for your V. It powers your inverter so your 110-VAC appliances and air conditioner will work, and it uses the same gas tank for fuel.
I hope this explains it for you.
leonard jaquez on May 27, 2017:
I have a 1975 executive, not sure what my onan generator does for my rv does it have a inverter 4000 watts gen.
Don Bobbitt (author) from Ruskin Florida on May 25, 2017:
Walter Brokx - Most motorhomes will have two switches (that control high-current relays) that will turn OFF or ON 12-VDC to your Chassis accessories and to your Coach accessories. They are for use when you park or store your RV so that your batteries do not get drained. Check for these switches first.
Typically, your RV generator will utilize your Coach batteries, but when you start your RV, these relays can be turned ON.
So, your most probable problem is having your Coach switch turned OFF.
Don Bobbitt (author) from Ruskin Florida on May 25, 2017:
Larry - First of all, most motorhomes have a safety feature where the fuel line for the generator only goes down into the fuel tank to the 1/4-full level.Tis is to prevent campers from becoming stuck in a far-away campsite with no fuel to get out.
Second, replace your generator fuel filters. Diesel fuel is pretty dirty and filters can get clogged.
These are the two most probable causes of your generator turning off.
Larry on May 22, 2017:
Is it necessary to have diesel engine running along with generator??Have a diesel 5500 Bigfoot and after about 10-15 minutes the generator shuts off don't mean to sound stupid
walter brokx on May 21, 2017:
Help what can i check or replace.
My c coach has 2 batteries to start the generator.
They are new batteries.
Wont turn over.
But when i start my Coach Ford 450 engine the generator will start.
IS there a relay or something ?
Don Bobbitt (author) from Ruskin Florida on October 20, 2016:
Vince - RV generators are air-cooled, so I'm not sure what yours is. But You didn't mention the fuel filter for the generator. Diesel fuel is a dirty fuel, so I would immediately change the fuel filter. On some Rv's the fuel filter is attached to the generator while on others, it may be mounted on the RV chassis near the Generator. This filter must be changed regularly, and I suspect it's your problem. If not, it's time to take your Rv to a service center so a PRO can check the Gen out.
vince on October 19, 2016:
i have a diesel gen i change the oil and filter drain water very little water came out i fill oil and water but only took 1/2 qt water it sart run then stop after 3 to 4 minn
help please thank vince
Don Bobbitt (author) from Ruskin Florida on August 22, 2016:
The two most common problems with RV generators are; the FUEL FILTER and the FUEL Pump. Over the years, I have had to replace both on several generators.
These two parts on these Onan 5500 generators are usually mounted under the generator. If you crawl under there you will see the pair mounted with a couple of screws.
If you are interested, I have written an article on how to replace these two items. It is called RV Generator maintenance, How to replace your Fuel Filer and fuel Pump.
Randy on August 21, 2016:
My gen wouldnt start or run. suspected bad carb. Onan 5500 Gold. spent the $$$ on the carb, installed it and viola, it ran, for about 5 min anyway, and not will not run again. HELP!!!
Don Bobbitt (author) from Ruskin Florida on February 03, 2014:
Teri- OK the steps and your internal lights are 12VDC. If they all work then your DC COACH system is OK.
If your Microwave actually works, by that I mean heats, then you have 110VAC coming into your Class-C OK.
If all of your breakers are actually functioning then your AC distribution system is OK. If your Roof AC works and you just do not have power to your appliances plugged into receptacles then you probably have ground fault receptacles that have kicked out. Find the master ground fault receptacle and reset it.
Teri on February 02, 2014:
I'm plugged into the house. I have a class c two days ago I had power today I have power only to the microwave. Nothing else. I've checked breakers and fuses and all appears well The steps work too but absolutely nothing else. Where else do I look
Don Bobbitt (author) from Ruskin Florida on July 23, 2013:
mona- Without any other information, on your RV or generator, I can say that almost all Onan generators are "self-contained" and that yourt fuel filter will be found under the covers.
Just find the fule line going into the generator, and it should go into the covered unit and connect to the fuel filter itself.
One other thing. Some Class-C motorhomes are built on truck frames and will have an original truck/van fuel tank. And, many of these tanks have the fuel PUMP built inside the tank itself. You should checkthat this is working properly also.
mona on July 22, 2013:
we have aclass c motorhome with a onan gas generator, we arent getting any fuel. does this generator have a fuel filter and if it does where is it located?