Fuel Pressure Regulator: Service and Repair

Fuel Pressure Regulator Valve N276

Function

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

If the pressure in the high pressure fuel circuit is too high, the fuel pressure regulator valve opens so a portion of the fuel leaves the fuel rail through the return line and goes back into the fuel tank.

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.

Special tools, testers and auxiliary items required

• Torque Wrench (40-200 Nm) (V.A.G 1332)


• Follow the safety precautions when working on the diesel direct injection system. Refer to => [ Safety Precautions ] Diesel Fuel Injection.

• Observe the rules for cleanliness. Refer to => [ Clean Working Conditions ] Diesel Fuel Injection.

Always follow these instructions before and during work.

Removing

- Remove the engine cover. refer to => [ Engine Cover ] Engine Cover.

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

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

• The fuel pressure regulator valve cannot be reused again.

- Dry the fuel pressure regulator valve.

- Disconnect the connector - arrow - from the fuel pressure regulator valve.






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

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

• Seal the fuel rail bore immediately with a suitable plug to prevent contaminants from entering.

Installing

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

• Check the sealing surface in the fuel rail bore.

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

- First, tighten the valve nut for the fuel pressure regulator valve by hand.

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

- Counter-hold at the valve housing hex and tighten the nut:

• Tightening specification, see - item 6 - in the => [ Fuel Rail and Injectors Overview ] Service and Repair.

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

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

- Read the Engine Control Module (ECM) Diagnostic Trouble Code (DTC) memory again. Refer to "Guided Functions" in the vehicle diagnostic tester.

- Install the engine cover. Refer to => [ Engine Cover ] Engine Cover.