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)
• Remote Control (V.A.G 1348/3A) with Adapter Cable (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. Refer to => Fuel Delivery and Air Induction Fuel Delivery and Air Induction
• Ignition switched off.
Fuel Pressure, Checking
FWD Sedan
- Remove carpeting in luggage compartment.
- Fold forward the right backrest of rear seat, if necessary.
FWD Wagon
- Remove left 1/3 backrest.
- Remove left side trim in luggage compartment and dirt tray.
All FWD
- Fold forward the right backrest of rear seat, if necessary.
- Remove luggage compartment floor trim.
- Remove cover for locking flange - arrows -.
- Carefully release and disconnect electrical harness connector - arrow - at locking flange.
AWD
- Remove rear seat bench.
- Remove cover for right locking flange - arrows -.
- Carefully release and disconnect electrical harness connector - arrow - at locking flange.
All Vehicles
- Connect (V.A.G 1348/3A) with (V.A.G 1348/3-3 ) with an adapter cable from (V.A.G 1594C) at terminal - 1 -.
- Cover 2nd connector terminal of (V.A.G 1348/3-3) with insulating tape to prevent short circuit - arrow -.
- Route (V.A.G 1348/3A) switch forward in engine compartment.
- Connect contact - 4 - to vehicle Ground (GND) using a self-made adapter cable.
- Connect alligator clip to battery "+".
- Pull rear engine cover off - arrows -.
CAUTION!
• Fuel system is under high pressure! 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 fuel line - arrow -.
- Connect (V.A.G 1318) with (V.A.G 1318/11 ) and (V.A.G 1318/12) in fuel line.
- Connect 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 the fuel system, by briefly pressing the remote control.
- 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 6 bar positive pressure
If the specification is not obtained:
- Check delivery quantity of fuel pump.
Residual Pressure, Checking
- Check for leaks and for residual pressure by observing the pressure loss on the pressure gauge.
• After 10 minutes there must be a residual pressure of at least 3.75 bar.
If the residual pressure drops below 3.75 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.
• Replace fuel filter with integrated fuel pressure regulator.
• Replace fuel pump.
Assembly is in reverse order of removal, note the following:
• Before disconnecting pressure gauge, release pressure by opening shut-off valve. Hold a container in front of connection for this.
Tightening Specifications
