Fuel Pump Check Valve, Checking

Fuel Pump, Checking

Special tools, testers and auxiliary items required

• Pressure Tester (VAS 6550)

• Remote Control (V.A.G 1348/3A)

• Test Instrument Adapter/DSO (5-pin) (VAS 5565)

• Hand Held Multi-Meter (V.A.G 1526D) with Current Clamp (V.A.G 1526B/2)

• Wrench (T10202)

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

• Measuring Container, 2 liter

• Vehicle Diagnostic Tester

Fuel Pump Check Valve, Checking

- Remove the rear seat bench.

- Remove the cover from the fuel delivery unit.





- First pull on the connector - arrow - without pressing the retainer to make sure it connected securely. If the connector was not connected correctly, it could cause a fault.





- Disconnect the connector.

- Check the contacts on the connector and the fuel delivery unit for damage.

- Connect the (VAS 5565) to the connector on the cover and on the fuel delivery unit.





- Connect the (V.A.G 1348/3A) to the (VAS 5565) and to the battery positive (+).

CAUTION!
Fuel supply line is under pressure! Wear protective goggles and protective clothing to prevent injuries and contact with skin. Before loosening the connection wrap a cloth around the connection. Loosen the connection carefully to release the pressure.

- Disconnect the fuel supply line - arrow - from the fuel filter.





- Connect the (VAS 6550) to the fuel supply line with the (VAS 6550/1). Hold the (VAS 6550/2) in the measuring container.





- Close the shut off valve - A - on the (VAS 6550) so the valve is perpendicular to the direction of flow.

- Operate remote control at short intervals, until a pressure of approximately 4 bar has built up.

CAUTION!
Danger of spraying when opening shut-off valve; wear protective goggles and protective clothing to prevent injuries and contact with skin. Hold container in front of free connection of pressure measuring device.

- If pressure builds up too high, lower excess pressure by carefully opening the shut off valve.

- Watch the pressure decrease on the pressure gauge. After 10 minutes the pressure must not drop below a 3 bar decrease.

If the pressure drops further:

- Check the line connections for leaks.

If no fault is detected in the wiring:

- Replace the fuel delivery unit if the fuel pump is faulty. Refer to => [ Fuel Delivery Unit ] Service and Repair.