Fuel Pressure and Residual Pressure Before High Pressure Pump, Checking

Fuel Pressure and Residual Pressure before High Pressure Pump, Checking

Special tools, testers and auxiliary items required

• Pressure Gauge (V.A.G 1318)

• Adapter (V.A.G 1318/11)

• Adapter (V.A.G 1318/12)

• Remote Control (V.A.G 1348/3 A) with Adapter Cable (V.A.G 1348/3-3)

• Connector Test Set (V.A.G 1594 C)

• Measuring container, fuel-resistant

Test Conditions

• Battery voltage min. 12.5 V.

• Fuel filter OK.

• Fuel tank at least 1/4 filled.

• Fuel Pump (FP) Control Module (J538) OK; checking. Refer to => Fuel Delivery and Air Induction Fuel Delivery and Air Induction

• Ignition switched off.

Fuel Pressure, Checking





- Remove rear seat bench.

- Unbolt cover for right locking flange - arrows -.

- Carefully release and disconnect electrical harness connector - arrow - at locking flange.





- Connect (V.A.G 1348/3 A) with (V.A.G 1348/3-3 ) to contact - 1 - using an adapter cable from the (V.A.G 1594 C).





- Using insulating tape, tape over the second contact of ( V.A.G 1348/3-3) to prevent a short circuit - arrow -.

- Connect contact - 4 - to vehicle Ground (GND) using a jumper cable from the (V.A.G 1594 C).

- Route the switch of the (V.A.G 1348/3 A) forward into the engine compartment.

- Push the cover over the positive terminal pick-off to the right - arrow 1 - and remove it upward - arrow 2 -.





- Release retaining clip - arrow - and open cover - 2 - over positive terminal pick-off.





- Connect alligator clip to vehicle battery (+) - 3 -.

• Ignore - 1 -.

- Pull rear engine cover off - arrows -.





- Remove bolts - 1 -.





- Disengage retaining clip - 2 - and remove rear engine cover bracket.

CAUTION!
Fuel system is under pressure! Before opening system, place clean rags around the connection. Then release pressure by carefully loosening the connection.

- Disconnect fuel supply line - arrow - at fuel rail.





- Connect (V.A.G 1318) to fuel line using (V.A.G 1318/11) and (V.A.G 1318/12).





- Connect an assisting hose - arrow - to pressure gauge and hold it in a measuring container.

- Open shut-off valve of pressure gauge. The lever points in the direction of flow.

- Bleed the fuel system, by briefly pressing the remote control.

- Close shut-off valve of pressure gauge. Lever stands perpendicular to direction of flow - arrow -.





- Hold the switch of the remote control until no more pressure increase is observed on the fuel pressure gauge.

• Specified value: Approximately 6 bar positive pressure

If the specification is not obtained:

- Check the fuel pump delivery quantity.

Residual Pressure, Checking

- Check for leaks and for residual pressure by observing the pressure loss on the pressure gauge.

• After 10 minutes there must be a residual pressure of at least 3 bar.

If the residual pressure drops below 3 bar:

• Check connection between fuel pressure gauge and fuel line for leaks.

• Check pressure gauge for leaks.

• Check fuel lines and their connections for leaks.

• Replace fuel filter with integrated fuel pressure regulator.

• Replace fuel pump.

Assembly is in reverse order of removal, note the following:

• Before disconnecting pressure gauge, release pressure by opening shut-off valve. Hold a container in front of connection for this.

• Tightening Specifications High pressure pump. Refer to => [ High Pressure Pump Assembly Overview ] High Pressure Pump Assembly Overview