Fuel Pressure Regulator: Service and Repair

Fuel Pressure Regulator Valve N276

The fuel pressure regulator valve - 2 - is located on the fuel rail and maintains a constant pressure inside the rail and in the fuel injector lines (fuel high pressure circuit).






If the pressure in the fuel 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 in the high pressure fuel circuit is too low, the fuel pressure regulator valve closes and seals the high pressure side from the low pressure side.

• The fuel pressure regulator valve must always be replaced if removed.

Special tools, testers and auxiliary items required

• Engine Bung Set (VAS 6122)

Removing

• Follow the guidelines for a clean working environment when working on the fuel system. Refer to => [ Clean Working Conditions ] Clean Working Conditions.

• Always follow these rules before and during work.

Installed location, see - item 13 - in the => [ Fuel Rail and Injector Overview ] Fuel Rail and Injector Overview.

- Remove the fuel rail. Refer to => [ Fuel Rail ] Fuel Rail.

- Before removing, clean the threaded area around the fuel pressure regulator valve (for example using commercially available coolant). Contamination must not enter the bore in the fuel rail.

• Clean carefully, the cleaner must not enter the connector.

- Dry the fuel pressure regulator valve.

- Counter hold at the housing hex and loosen the union nut. Then remove it by hand.

- Extract the contamination from the fuel rail bore (threads and sealing surface). Do not use mechanical tools.

- Seal the fuel rail opening with a plug from the engine bung set (VAS 6122).

Installing

Install in reverse order of removal. When doing this note the following:

• The fuel pressure regulator valve has a biting edge instead of a sealing ring and cannot be reused.

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

• Check the sealing surfaces on the fuel rail opening.

• Coat the fuel pressure regulator valve threads and biting edge with diesel fuel.

- Tighten the union nut by hand.

- Align the new regulator valve so that the connection line is not taut after connecting the connector.

- Counter hold the regulator valve at the housing hex in this position using an open end wrench or pliers (for example, water pump pliers).

- Use a suitable torque wrench with a 30 mm open end wrench to tighten the union nut.

- Install the fuel rail. Refer to => [ Fuel Rail ] Fuel Rail.

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

- Check the fuel system for leaks.

- 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 again.

Tightening Specifications