Fuel Pressure Regulator: Testing and Inspection

Checking Fuel Pressure Regulator:

Requirements

- Fuel pump delivery quantity OK

- Fuel pressure gauge VAG 1318 or equivalent.

Procedure

- Remove plug from test port on fuel rail.

- Connect pressure gauge VAG 1318 or equivalent, to test port on fuel rail.

CAUTION: The pressure tester shutoff valve, if equipped, must be closed, (arrow).

- Start engine and let idle.

- Observe fuel pressure, must be approximately 3.5 bar.

- Disconnect vacuum hose from fuel pressure regulator (arrow).

- Fuel pressure must increase to approximately 4.0 bar.

If pressures are not reached.

- Replace fuel pressure regulator.

If pressures are exceded.

- Check return lines and hoses for restrictions or blockage.If lines and hoses are OK replace fuel pressure regulator.

- Switch OFF ignition.

- Check residual pressure and for leakage by interpreting pressure drop on gauge.

- After 10 minutes, must still be 2.5 bar(minimum).

If the residual pressure drops below 2.5 bar.

- Start engine and let idle.

- After pressure increases; switch OFF ignition and simultaneously clamp the fuel return line at the fuel rail.

- Watch for a pressure drop on VAG 1318 gauge.

If pressure does NOT drop.

- Replace fuel pressure regulator.

If pressure drops.

- Check fuel pump check valve.

- Check hose connections and O-rings on fuel rail.

- Check fuel injectors for leakage.

- Check pressure gauge for leakage.

CAUTION: Before disconnecting the fuel pressure gauge, reduce the fuel pressure by opening the fuel shutoff valve. Catch any escaping fuel in a container.