How to Replace a Fuel Pressure Regulator

Fuel pressure regulator and injectors mounted on a fuel rail.
Fuel pressure regulator and injectors mounted on a fuel rail. | Source

You can replace a fuel pressure regulator with a few common tools at home in most vehicle models, those with systems with Throttle Body Injection (TBI) or newer ones with Electronic Fuel Injection (EFI) systems.

The pressure regulator has one of the most important jobs in the system: Control the amount of fuel pressure to each injector.

So a failed regulator can cause one of two things: It may increase fuel pressure beyond the required parameters and provide too much fuel to the engine, increasing emissions; or fail to maintain sufficient pressure and starve the engine, causing it to lose power, affect performance (misfire), make it hard to start or to not start at all.

Just like any other component, fuel pressure regulators wear out—the spring may weaken, the diaphragm may allow fuel through, or some other internal or external component may stop doing its job.

You don't need any special skills for this task, and, in many models, it only takes about 30 minutes to install a replacement. And if you decide to do it yourself, you may save over $200.00 dollars in repair costs, depending on your particular model.

This simple guide tells you how to do it, what you need to pay attention to, and the safety precautions you need to take for a successful repair job.

Symptoms of a failed fuel pressure regulator:
Increased fuel pressure
Increased emissions
Increased fuel consumption
Insufficient fuel pressure
Hard to start
No start
Schrader valve on a fuel rail.
Schrader valve on a fuel rail. | Source

Relieving Fuel System Pressure

Before you start working on the fuel system, there's a couple of things you need to do: First, park in an area with enough ventilation and away from appliances with open flames like water heaters and dryers—fumes released by the fuel system ignite easily. Second, you'll need to relieve system pressure.

To relieve system pressure:

* On some TBI models, system pressure drops a few seconds after turning off the engine.

* However, on TBI models and multiport fuel injection systems you can remove the fuel pump fuse or relay, start the engine and let it idle until it stalls.

* Electronic fuel injection systems use a Schrader valve as well on the fuel rail. With the engine cool, you can cover the valve with a rag and carefully depress the valve with a screwdriver. Use the rag to catch the squirt of fuel that comes out of the valve. Then, loosen the fuel filler cap to remove pressure from the gas tank.

* After that, disconnect the negative (black) battery cable.

* Now, you can proceed to replace the fuel pressure regulator.

Typical throttle body injection system.
Typical throttle body injection system. | Source

How to Replace a Fuel Pressure Regulator on a TBI System

After releasing fuel system pressure and disconnecting the battery:

1. Remove the air cleaner assembly from the throttle body injection unit to gain access to the fuel pressure regulator.

2. After removing the air filter housing, you'll see the fuel charging assembly, which includes the throttle body and fuel injector. Usually, the fuel injector mounts on top of the fuel pressure regulator.

3. Unplug the electrical connection from the fuel injector.

4. Unscrew and carefully remove the fuel injector retainer, which holds the fuel injector in place. The retainer mounts on top of the fuel pressure regulator cover. Keep screws and small parts you need to remove in a safe place so you don't lose them.

5. Move the fuel injector to the side.

NOTE: On some models like Honda and Nissan, you may need to disconnect the fuel hose from each end of the fuel pressure regulator before you can replace it. Also, on some models like GM and Ford, you'll replace the pressure regulator using a new kit. With some Chrysler and Nissan models, you'll remove the pressure regulator as a single unit.

6. Finish removing the screws holding the pressure cover in place. As you remove the screws, hold the cover in place with one hand, so the spring under the cover doesn't send the cover flying off.

7. Carefully lift the pressure cover.

8. Pay attention to the order in which the components are assembled. You'll have to reassemble those components in the same order. Depending on your particular model, your fuel pressure regulator may include a pressure regulator cover, regulator diaphragm cup, diaphragm spring, regulator body, regulator diaphragm, and regulator outlet tube.

9. Check the old components with those included in your new kit, and replace those included with your new kit.

10. Once you've installed the new components or placed the new regulator in position, tighten the mounting bolts.

11. Reinstall the fuse or relay fuel pump and connect the negative battery cable.

12. Turn the ignition key to the On position and check for fuel leaks around the new pressure regulator.

13. Replace the air cleaner assembly.

When installing the fuel pressure regulator, all fuel lines should properly tighten.
When installing the fuel pressure regulator, all fuel lines should properly tighten. | Source

How to Replace a Fuel Pressure Regulator on a Multiport Fuel Injection System

On Multiport Fuel Injection systems, you'll find the fuel pressure regulator connected to a fuel pipe that goes to the fuel rail with the fuel injectors. This guide helps you replace a common regulator on these type of systems.

However, your particular regulator assembly configuration may differ from the one described here. If so, consult the service manual for your particular vehicle make and model, if necessary. You can buy an inexpensive aftermarket manual online or at most auto parts stores.

1. After relieving fuel pressure from the system, remove any covers to gain access to the fuel pressure regulator. NOTE: On some vehicle models, it's necessary to remove an intake plenum to reach the regulator. Consult your vehicle service manual, if necessary.

2. Carefully pull off the vacuum hose from the regulator.

3. Loosen the fuel return line fitting on the regulator. You may need to hold the molded regulator-nut with a wrench while loosening the line-nut with another wrench. On some models, the return line uses a quick connect fitting you can release with an inexpensive tool you can buy at most auto parts stores.

4. Disconnect the return line.

5. On some models, you don't need to disconnect the return line, but unscrew the regulator mounting (two or three) bolts using an Allen or hex wrench. On other models, you may need to unscrew the fuel lines and regulator from a fuel supply manifold, plus mounting brackets. Consult your repair manual, if necessary.

6. Remove the regulator from the line or mounting base.

7. Thoroughly clean the gasket mating surface on the regulator mounting base.

8. Lightly coat the new regulator O-ring with clean engine oil before installation.

9. Set the O-ring and new gasket in place on the new regulator.

10. Install the new regulator.

11. Connect the fuel line, if you had to disconnect it.

12. Connect the vacuum line to the regulator.

13. After reinstalling any shields or covers to the engine, and replace the fuel pump fuse, if you had to remove it.

14. Restore system pressure by turning the ignition key ON for five seconds and then to the OFF position. Repeat this sequence at least four more times.

15. Check for fuel leaks around the fuel pressure regulator.

16. Reinstall any other components you had to remove to reach the pressure regulator.

The following video shows you how to replace a fuel pressure regulator on an early EFI system.

Once you replace the fuel pressure regulator, it's a good idea to maintain the system to prevent engine performance problems. Add a quality fuel additive to the fuel tank at least twice a year to keep fuel injectors clear and remove buildup. Also, replace the fuel filter every year to prevent fuel flow restriction and help extend the service life of the fuel pump. On the long run, you'll save on repairs and gas.

How much you know of bad fuel pressure regulators?

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