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.

- Remove rear seat bench.

- Remove the locking flange cover - arrows -.





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





• Ignore - 2 -.

- Connect the 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 -.

- Cover 2nd connector terminal of Adapter Cable (V.A.G 1348/3-3) with insulating tape to prevent short circuit - arrow -.





- Connect terminal - 5 - to the vehicle ground using a jumper cable from the Connector Test Set (V.A.G 1594C).

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

- Connect the 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.

- Remove fuel filler cap from fuel filler tube.

- Remove engine cover.


• Before opening high pressure components of the fuel injection system, pressure must be relieved to residual pressure. Refer to => [ Before Opening High Pressure Fuel Injection System ] Service and Repair.

• Then wrap a clean rag around the connection and relieve residual pressure by carefully loosening the connection.

Disconnect the Fuel Supply Line - arrow - at the Distribution Pipe on Engines with Magnesium Intake Manifolds.





Disconnect the Fuel Supply Line - arrow - at the Distribution Pipe on Engines with Plastic Intake Manifolds.





- Connect Fuel Inj. Pressure Gauge-CIS (V.A.G 1318) with adapter and Adapter Set (V.A.G 1318/10-12) in fuel line.





- 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 flow direction.

- 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 the specification is not obtained:

- Check the fuel pump delivery quantity.

Checking residual pressure:

- 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 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.

• Check the fuel pump delivery quantity.

• Replace the fuel filter with the integrated fuel pressure regulator.

• Fuel pump check-valve is faulty.

Assembly is in 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.

- Install the fuel supply line on the distribution piece. Make sure it is clean and there are no leaks.

Tightening Specifications