Fuel Pressure Regulator: Service and Repair

Fuel Pressure Regulator Valve N276

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

If the pressure in the high pressure fuel 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 regulator valve closes and seals off the high pressure side from the low pressure side.

The fuel pressure regulator valve cannot be reused again.

Removing

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. Refer to => [ Engine Cover ] 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 fuel rail.

• Clean carefully, the 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 hex and loosen the union nut. 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 has a biting edge instead of a seal 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 nut hand tight.

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

Tighten the union nut in 2 steps.

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

Then rotate the union nut back 90° (1/4) turn while counter holding at the housing hex.

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

- After installing, Allow the engine to run at a moderate speed for a few minutes and then turn it off.

- Check the fuel system for leaks. Refer to => [ Fuel System, Checking for Leaks ] Fuel System, Checking for Leaks.

• If the fuel pressure regulator valve or the high pressure pump has been replaced, then the adaptation values for the regulator valve must be reset, only via the vehicle diagnostic tester: Guided Functions, resetting the adaptation values for the fuel pressure regulator valve.

- Check the Diagnostic Trouble Code (DTC) memory. Refer to the vehicle diagnostic tester.

- 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 one more time, refer to the vehicle diagnostic tester.