Fuel Pressure Regulator: Service and Repair

Fuel Pressure Regulator Valve (N276)

Special tools, testers and auxiliary items required

• Socket wrench

• 30 mm open end wrench

• 33 mm open-end wrench

The fuel pressure regulator valve - 2 - is located inside the fuel rail and maintains a constant pressure inside the fuel 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 fuel 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 cannot be used again.

Removing


• Follow the guidelines for clean working conditions when working on the fuel system. Refer to => [ Fuel System ] Fuel System.

• Always follow these rules before and during work.

- Remove engine cover. Refer to => [ Engine Cover ] Service and Repair.

- Remove the noise insulation from the cylinder head cover.

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

- 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, cleaner must not enter the connector.

- Dry the fuel pressure regulator valve.

- Counter hold at the housing hex bolt 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 immediately with a plug to prevent dirt from entering.

Installing

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

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

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

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

- Tighten union nut by hand.

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

- Hold the regulator valve by the housing hex bolt in this position using an open-end wrench or with pliers.

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

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

• Tightening specifications, refer to => [ Fuel System Overview ] Fuel System Overview, Diesel.

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

- Check fuel system for leaks.

- Check the Diagnostic Trouble Code (DTC) memory.

- 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.