How to Replace a Fuel Filter

A clogged fuel filter will restrict fuel flow to the engine.
A clogged fuel filter will restrict fuel flow to the engine. | Source

You can replace the fuel filter in a few minutes in most cases, depending on its location.

Most modern vehicles use an in-line fuel filter that connects to the main line of the fuel system. Some models may use a filter inside the fuel tank, which requires lowering the tank and removing the fuel pump assembly to replace the filter. Still, other vehicles—gasoline or diesel—use a special metal canister or glass bowl connected to the fuel line with a removable cap to replace the filter element inside. On old models with a carburetor, you can find a disposable filter element where the main fuel line connects to the carburetor body.

The filter helps trap particles of dirt, water, rust and other contaminants before they reach the engine. So most car manufacturers recommend replacing the fuel filter at least once a year (about 12,000 miles—19,213 km) when impurities trapped by the filter element begin to affect fuel flow and engine performance.

The average car owner can replace the filter at home using a few common tools. Taking the proper safety precautions, it'll take you about an hour or less to restore much needed power to the engine.

Before you start, though:

* Choose a well ventilated area to work on your car.

* Park the car away from appliances with open flames, like those that run with natural gas (water heater or clothes dryers). Fuel vapor fumes may catch fire just with a small spark or flame.

* Also, if you know you have to lift the car to gain access to the filter, park you car on a flat surface with plenty of room around to work on your vehicle.

Here, we'll take a look at how to replace an in-line fuel filter, but if your car uses an in-tank filter, you still can follow this general directions. But, consult your vehicle repair manual so that you know how to lower your fuel tank, disconnect the lines and remove the fuel pump assembly. Some models give quick access to the pump assembly through a quick access underneath the back seat of the car, so you don't have to lift the car to lower the tank.

Types of Automotive Fuel Filters
Bowl type
Canister type
In-line fuel filter
Threaded fuel filter
Pleaded paper replaceable filter
Fuel pump filter

Locating the Fuel Filter

Most vehicle models use an in-line fuel filter. You may find it in the engine compartment, mounted on the firewall; others have the filter under the vehicle, mounted on the frame near the driver's side, or close to the fuel tank (you may need to lift the vehicle to see the filter).

On old models with a carburetor, you'll find the filter between the inlet fuel line and the carburetor. As mentioned before, some vehicles also use a metal or glass container to house the filter element. The containers have a removable cap to replace the filter.

If you don't see the filter, follow the main fuel line from the engine towards the fuel tank, if necessary, or consult the vehicle repair manual for your particular model to locate the filter.

You can find the Schrader valve on the fuel rail around the top of the engine.
You can find the Schrader valve on the fuel rail around the top of the engine. | Source

Relieving Fuel System Pressure

After locating the filter, you need to depressurize the system. To relieve system pressure, loosen the fuel filler cap and remove the pump fuse or relay. Your car owner's manual or vehicle service manual will tell you where to find the fuse, but look in the "power distribution center" under the hood, or in a fuse panel under the dashboard. Under the lid of the fuse box you may find a description and identification of every fuse in that panel.

After removing the fuse, start the engine. Let it idle until it stalls. Then crank the engine for a couple of seconds. That's it. You are ready to work on the filter.

Alternatively, if your car has a test-port valve—similar to the air valve on your car tires—you can use this valve to relieve system pressure as well (most vehicle with fuel injectors use this type of valve). You'll find the valve on the fuel rail that connects to the fuel injectors on top of the engine. Wait for the engine to cool; then, wrap a shop rag around the valve and depress the needle inside the valve with a screwdriver. The rag will catch the squirt of fuel as you depress the valve.

Check the next video so that you have an idea how to relieve fuel system pressure.

Replacing the Fuel Filter

After relieving fuel system pressure:

1. Disconnect the negative (black) battery cable.

2. If you need to lift the car to access the fuel filter, secure the vehicle using one or two jack stands, block the wheels that remain on the ground and engage the parking brake. And use safety glasses to prevent dirt and fuel from entering your eyes.

3. Clean the fittings on both fuel lines connecting to the filter using a shop rag. This will prevent contamination of the system.

4. To disconnect the lines from the filter:

* You may need to remove a hairpin clip—on each fitting—securing the fuel line to the filter.

* On other models, you may need to unscrew the nut that holds the line to the threaded fitting (aka banjo fitting) on the fuel filter. To do this, hold the nut closer to the filter with a regular wrench and unscrew the line nut using a line wrench. Using this special wrench will prevent you from damaging the lines. Also, see the location of the washers on the screws, so that you know where to install the new ones that come with your new filter.

* On models with bowl-type containers, unscrew the cap from the container to gain access to the filter element.

* If your engine uses a carburetor, use a line wrench to disconnect the main fuel line from the carburetor. Don't lose the O-ring and spring inside the filter housing, so that you can reinstall them as well. Or use the parts that come with your kit.

* On other models, you may have to use a special plastic tool to push in the plastic ring at the end of the line to unlock it; on some GM models you can use pliers to depress the quick-connect fittings (tabs) to release the line.

5. On in-line fuel filters located under the vehicle, you may have to unscrew the clamp or bracket holding the filter in place. Before you remove the filter from its mounting position, look at the arrow printed on the filter case. When mounting the new filter, the arrow on the new filter has to point in the same direction.

6. Use a shop rag to absorb the residual fuel in the lines when disconnecting the filter.

7. After removing the filter or filter element, compare it to the new one so you know you have the correct replacement.

8. Now you can follow these same steps in reverse order to install the new unit.

9. When finished, reconnect the battery, crank up the engine and check for fuel leaks on both sides of the new filter.

You may find the fuel filter near the fuel tank.
You may find the fuel filter near the fuel tank. | Source

You only need a few minutes to replace a fuel filter on most vehicle models using a few common tools. The filter only costs a few dollars and not only restores proper fuel flow and power to the engine, but helps extend the service life of the fuel pump as well. So you save a few hundred dollars in repairs by changing the filter at regular intervals or at the recommended manufacturer schedule. And when you do it yourself, you stretch your car maintenance budget even more. Use that money to service other systems in your car or replace some other aging components.

Test Your Knowledge of Clogged Fuel Filters

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