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)

• 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 kit (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 retainers - arrows - of the cover for sealing flange.





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





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





- Using insulating tape, tape over the second contact of connection (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 connector test set (V.A.G 1594 C).

- Connect alligator clip to vehicle battery (+).

- 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 residual pressure by carefully removing connection.

- Disconnect fuel supply line - arrow -.





- Attach Fuel Line Feed Adapter (V.A.G 1318/23) and Adapter (V.A.G 1318/17-1) to Fuel Inj. Pressure Gauge-CIS (V.A.G 1318).





- Push adapter (V.A.G 1318/17-1) onto the disconnected fuel supply line.

- Attach Adapter (V.A.G 1318/11) to Fuel Inj. Pressure Gauge-CIS (V.A.G 1318).

- Push an assisting hose - arrow - onto it and hold it into a measuring container.

- Open shut-off valve on Fuel Inj. Pressure Gauge-CIS (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 Fuel Inj. Pressure Gauge-CIS (V.A.G 1318). Lever stands perpendicular to direction of flow - arrow -.





- Press remote control switch until pressure increase is no longer observed on Fuel Inj. Pressure Gauge-CIS (V.A.G 1318).

• Specified value: Approximately 6 bar (4 to 8 bar) positive pressure

If specification is not obtained:

- Check delivery rate of fuel pump.

Residual Pressure, Checking

- Check for leaks and residual pressure by observing pressure drop on Fuel Inj. Pressure Gauge-CIS K-Jetronic (V.A.G 1318).

• 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 Inj. Pressure Gauge-CIS K-Jetronic (V.A.G 1318) and fuel supply line for leaks.

• Check Fuel Inj. Pressure Gauge-CIS (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 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.

- Reconnect fuel supply line (pay attention to cleanliness and leaks).