Fuel Pressure Regulator: Service and Repair

Fuel Pressure Regulator Valve

Function

The fuel pressure regulator valve is located in the rail element (high pressure reservoir) and maintains a constant pressure in the rail element 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 rail element 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 (V.A.G 1332)

CAUTION!
• Follow the safety precautions when working on the diesel direct injection system. Refer to --> [ Safety Precautions ] Safety Precautions.

• Observe rules for cleanliness. Refer to --> [ Clean Working Conditions ] Clean Working Conditions.

Always follow these instructions before and during work.

Removing

- Remove engine cover --> [ Engine Cover ] Engine Cover.

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

• Clean carefully, cleaner must not enter the connector.

- Dry the fuel pressure regulator valve.

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





- Counterhold at the housing hex bolt and loosen union nut. Then remove it by hand.

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

• Seal the rail element 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 on the rail element bore.

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

- First tighten the union nut on the fuel pressure regulator valve by hand.

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

- Counterhold at the housing hex bolt and tighten the union nut:

• Tightening specifications --> [ 6 ] Removal and Replacement.

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

- Check fuel system for leaks. Refer to --> [ Fuel System, Performing Leak Test ] Testing and Inspection.

- Read the ECM DTC memory again.

- Install engine cover --> [ Engine Cover ] Engine Cover.