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)
• Pressure Gauge Adapter (V.A.G 1318/10-12)
• Remote Control (V.A.G 1348/3A) with Remote Control (V.A.G 1348/3-3)
• Measuring container, fuel-resistant
Test Conditions
• Battery voltage at least 12.5 V.
• Fuel filter OK.
• Fuel tank at least 1/4 filled.
• Fuel pump control module (J538) OK; checking.
• Ignition switched off.
Fuel Pressure, Checking
- Remove the rear bench seat.
- Remove the bolts - arrows - and remove the cover for the right locking flange.
- Carefully release and disconnect electrical harness connector - arrow - at locking flange.
- Connect the (V.A.G 1348/3A) using the (V.A.G 1348/3-3) and cable from the connector test set (V.A.G 1594C) to the terminal - 5 -.
- 2. Tape (V.A.G 1348/3-3) with insulating tape - arrow - to prevent a short circuit.
- Route (V.A.G 1348/3A) toward front in engine compartment.
- Connect alligator clip to ground (GND) point in engine compartment.
- Connect the contact - 1 - to the battery positive with a self-made adapter cable.
• For safety reasons, install a fuse - A - in the cable.
- Remove the bolts - arrows -, remove the air guides - 1 - and - 2 -.
There is a risk of injury because the fuel is under very high pressure.
• Before opening high pressure area of the fuel injection system, fuel pressure must be relieved to residual pressure.
- Reduce fuel pressure in high pressure area. Refer to => [ Before Opening High Pressure Fuel Injection System ] Service and Repair.
- Remove the fuel supply hose from the high pressure pump - arrow - and free it up.
- Connect the (V.A.G 1318) with adapters (V.A.G 1318/11) and (V.A.G 1318/15) in the fuel line.
- Connect assisting hose - arrow - on pressure gauge and hold in a measuring container.
- Open the shut-off valve on the pressure gauge.
• The lever points in the direction of flow.
- Bleed fuel system by briefly pressing remote control.
- Close the shut-off valve on the pressure gauge.
• Lever stands perpendicular to direction of flow - arrow -.
- Press the remote control switch long enough until the pressure gauge stops registering an increase in pressure.
• Specified value: approximately 6 bar pressure.
- If the specified value is not reached, check the fuel pump delivery rate.
Residual Pressure, Checking
- Check for leaks and constant pressure, watch the manometer to see if there is a drop in pressure.
• After 10 minutes there must be a residual pressure of at least 3 bar.
If the holding pressure drops below 3 bar:
• Check connection between pressure gauge and fuel line for leaks.
• Check the pressure gauge for leaks.
• Check fuel lines and their connections for leaks.
• Replace the fuel filter with an integrated fuel pressure regulator.
• Replace the fuel pump.
Assembling
Assembly is performed in reverse order of removal, noting the following:
There is a risk of injury because the fuel is under very high pressure.
• Before disconnecting pressure gauge, release pressure by opening shut-off valve. Hold a container under the connection.
- Connect the fuel supply hose - arrow - to the high pressure pump. Make sure the hose is clean.
• Tightening specifications, refer to => [ High Pressure Pump Overview ] High Pressure Pump Overview
- Install the rear bench seat.
• Check fuel system for leaks.