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

• Fuel Inj. Pressure Gauge-CIS (V.A.G 1318)

• Adapter (V.A.G 1318/11)

• Adapter (V.A.G 1318/17-1) from Adapter Kit (V.A.G 1318/17)

• Double Connection (V.A.G 1318/23)

• 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) or (V.A.G 1594 A)

• Measuring container, fuel-resistant

Test Conditions

• Battery voltage at least 12.5 Volts.

• Fuel filter OK.

• Fuel tank at least 1/4 full.

• Fuel Pump (FP) Control Module (J538) OK; checking

• Ignition switched off.

Test Sequence

- Remove rear seat bench.

- Unclip the retainers - arrows - of the cover for sealing flange.





- 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 - 5 - to vehicle ground (GND) using a jumper cable from the (V.A.G 1594 C).

- Connect alligator clip to vehicle battery positive.

- Remove fuel filler cap from fuel filler tube.


The fuel system is pressurized (low pressure). Wear protective eyewear and clothing in order to avoid injuries and contact with skin. Before opening the fuel system, place a rag around the connection. Then reduce the pressure by carefully removing the connection.

- Pull the release button to disconnect the fuel supply line - 3 -.





• If equipped, the fuel return line - 2 - and the vacuum line - 1 - remain connected.

- Connect the (V.A.G 1318) with the adapter on the connection for the fuel supply line.





- Place the hose - arrow - into a measuring container.

- Open the shut-off valve on the (V.A.G 1318). The lever points in the direction of flow.

- Bleed fuel system by pressing remote control briefly.

- Close shut-off valve on (V.A.G 1318). Lever stands perpendicular to direction of flow - arrow -.





• The (V.A.G 1318) shut-off tap must be on the side of the measuring container.

- Hold the switch of the remote control until no more pressure increase is observed on the (V.A.G 1318).

• Specified value: approximately 6 bar (4 to 8 bar)

If the specification is not obtained:

Residual Pressure, Checking

- Check for leaks and residual pressure by observing pressure drop on (V.A.G 1318).

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

If the residual pressure drops below 3 bar:

• Check the connection between the (V.A.G 1318) and the fuel supply line for leaks.

• Check the (V.A.G 1318) for leaks.

• Check fuel lines and their connections for leaks.

• Replace fuel filter with integrated fuel pressure regulator. Then repeat test.

• If the fuel filter is OK, replace fuel pump.

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

- Ignition must be switched off.





• Before disconnecting pressure gauge, release pressure by opening shut-off valve. Hold assisting hose in a container when doing so.

- Install the fuel supply line again (check for cleanliness).