Fuel Pressure Regulator: Service and Repair

Fuel Pressure Regulator Valve

The fuel pressure regulator valve is located in the right fuel rail (high pressure reservoir) for cylinder bank 1 and maintains a constant pressure in the reservoir and the injector lines.

If the pressure in the high pressure circuit is too high, the regulator valve will open so that some of the fuel flows from the rail back into the fuel tank via a return line.

If the pressure is too low, then the check valve closes and seals off the high pressure side from the low pressure side.

The fuel pressure regulator valve (N276) cannot be used again.

Removing

CAUTION!
Follow the guidelines for clean working conditions when working on the fuel system. Refer to => [ Clean Working Conditions and Fuel System Work Instructions ] Clean Working Conditions and Fuel System Work Instructions.

Always follow these instructions before and during work.

- Remove the engine cover.

- Before removing, clean the threaded area around the fuel pressure regulator valve with a commercially available detergent. Dirt must not enter the hole in the high pressure reservoir.

• Clean carefully, cleaner must not enter the connector.

- Dry the fuel pressure regulator valve.

- Disconnect the connector from the fuel pressure regulator valve.

- Counter hold at the housing bolt and loosen the union fitting. Then remove it by hand.

- Suction any dirt out of the hole in the fuel rail, the threads and the sealing surface. Do not use mechanical tools.

• Seal the hole in the fuel rail with a plug to prevent dirt from entering.

Installing

• The fuel pressure regulator valve does not have a seal, but rather a biting edge and cannot be reused.

• Check the new fuel pressure regulator valve sealing surface and threads for damage.

• Check the sealing surface on the hole in the fuel rail.

• The threads on the fuel pressure regulator valve must be free of oil and grease.

- Tighten the union fitting by hand.

- Align the fuel pressure regulator valve so the connecting line is not taut after connecting the connector.

Tighten the union fitting in 2 steps:

1. Step: 60 +/-5 Nm, counter hold the housing bolt while doing this

Then rotate the union fitting back 90° (1/4) additional turn while counter holding at the housing bolt.

2. Step: 80 +/+5 Nm, counter hold the housing bolt while doing this

- After installing, let the engine run at a moderate speed for a few minutes and then shut it off.

- Check the fuel system for leaks. Refer to => [ Fuel System, Performing Leak Test ] Fuel System, Performing Leak Test.

• If the fuel pressure regulator valve or the high pressure pump must be replaced, the adaptation values of the regulator valve must be reset via the vehicle diagnostic tester: guided functions, resetting the adaptation values of the fuel pressure regulator valve.

- Check the Diagnostic Trouble Code (DTC) memory. Refer to => [ Engine Control Module DTC Memory, Checking and Erasing ] Scan Tool Testing and Procedures.

- Perform a road test where the accelerator pedal is pressed all the way down at least one time. Then check the high pressure area again for leaks.

- Check the DTC memory again. Refer to => [ Engine Control Module DTC Memory, Checking and Erasing ] Scan Tool Testing and Procedures.