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 K-Jetronic (V.A.G 1318)

• Pressure gauge adapter (V.A.G 1318/10-12)

• Connector test set (V.A.G 1594C)

• Remote Control (V.A.G 1348/3A) with adapter cable (V.A.G 1348/3-3)

• Measuring container, fuel-resistant

• Protective gloves

Fuel Pressure, Checking

• Battery voltage at least 12.5 Volts.

• Fuel filter OK.

• Fuel tank at least 1/4 filled.

• Fuel Pump (FP) Control Module (J538) OK.

• Ignition switched off.

Fuel Pressure, Checking

- Remove rear seat bench.

- Remove locking flange cover - arrows -.





- Disconnect electrical harness connector - 1 - at locking flange.





• Ignore - 2 -.

- Connect remote control (V.A.G 1348/3A) with adapter cable (V.A.G 1348/3-3) with an adapter cable from the connector test set (V.A.G 1594C) at terminal - 1 -.

- Using insulating tape, tape over the second terminal on the adapter cable (V.A.G 1348/3-3) - arrow - to prevent a short circuit.





- Connect terminal - 5 - to the vehicle ground using a jumper cable from the connector test set (V.A.G 1594C).

- Connect remote control (V.A.G 1348/3A) to item - A - in the terminal box in the plenum chamber (battery +). For safety reasons, install a fuse (10 A) in the wiring connection.

- Route Remote Control (V.A.G 1348/3A) switch forward in engine compartment.

- Remove seal - arrow -.





- Unclip plenum chamber cover - 2 - and remove it.

• Ignore - 1 and 3 -.

- Release retainer - arrow A - and open cover - arrow B -.





- Connect alligator clip to the battery jump start terminal (U6) - A - in the terminal 30 wire junction 2 (TV22) in plenum chamber.





- Remove fuel filler cap from fuel filler tube.

- Remove front engine cover.

- Remove fuel supply line - arrow - from the high pressure pump.






There is a risk of injury because the fuel is under high pressure.

• To reduce pressure in fuel system, lay a clean cloth around the connector and carefully loosen connector.

- Connect fuel injector pressure gauge (V.A.G 1318) to the fuel supply line using an adapter.





- 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 fuel system by pressing remote control briefly.

- 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 5.5 bar (4.5 to 6.5 bar) positive pressure.

If specification is not obtained:

- Check delivery quantity of Fuel Pump (FP).

Residual Pressure, Checking

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

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

If 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.

• Check delivery quantity of Fuel Pump (FP).

• Replace fuel filter with integrated fuel pressure regulator.

• Fuel pump check-valve is faulty.

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

- Switch off ignition.

• Before removing pressure gauge, release fuel pressure by opening shut-off valve. Hold a container under the connection.

- Connect fuel supply line - arrow - to the high pressure pump.





• Check fuel system for leaks.