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)
• Remote control (V.A.G 1348/3A) with adapter cable (V.A.G 1348/3-3)
• Connector test set (V.A.G 1594C)
• Measuring container, fuel-resistant
• Protective gloves
Checking fuel pressure
• transfer Fuel Pump (FP) (G6) fuse from fuse holder at left in E-box plenum chamber OK.
• Battery voltage at least 12.5 V.
• Fuel filter OK.
• Fuel tank at least 1/4 filled.
• Fuel Pump (FP) control module (J538) OK.
• Ignition switched off.
Risk of injury from fuel.
• Before opening the fuel system, lay a clean cloth around the connection point and carefully loosen it, which lowers the pressure.
• Fuel Pump (FP) control module (J538) is located at front of fuel tank below exhaust system and driveshaft.
Risk of burning.
• Allow exhaust system to cool.
- Disconnect electrical connector - 2 -.
• Ignore - 1, 3 and arrows -.
- Connect connector terminal - 2 - with an adapter cable from connector test kit (V.A.G 1594C) to chassis ground (GND).
- Connect VAG 1348 remote control (V.A.G 1348/3A) with adapter cable (V.A.G 1348/3-3) to terminal - 1 - on connector.
- 2. Tape adapter cable connector terminal (V.A.G 1348/3-3) with insulating tape - arrow - to prevent a short circuit.
- Route VAG 1348 remote control (V.A.G 1348/3A) toward front in engine compartment.
- Release retaining clip and open cover - A - over positive terminal pick-off.
- Connect alligator clip to positive terminal pick-off.
- Remove fuel filler cap from fuel filler tube.
Risk of injury from fuel.
• Before opening the fuel system, lay a clean cloth around the connection point and carefully loosen it, which lowers the pressure.
- Disconnect fuel line - 2 -.
• Ignore - 1 -.
- Connect fuel injection pressure gauge (V.A.G 1318) with adapter (V.A.G 1318/11) and (V.A.G 1318/12) in the fuel line.
- Connect assisting hose - arrow - on Pressure gauge and hold in a measuring container.
• The lever points in direction of flow.
- Bleed fuel system by briefly pressing remote control.
- Close pressure gauge shut off valve.
• Lever stands perpendicular to direction of flow - arrow -.
- Press remote control switch until pressure no longer climbs on pressure gauge.
• Specified value: approximately 6 bar positive pressure
- If specified value is not reached, check fuel pump delivery quantity.
Checking Residual Pressure
- Check for leaks and residual pressure by observing pressure drop on gauge.
• After 10 minutes there must be a residual pressure of at least 3.75 bar.
If residual pressure drops below 3.75 bar:
• Check connection between 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.
Assembling
• Tightening specifications => [ Fuel Rail and Injectors, Assembly Overview ] Fuel Rail and Injectors, Assembly Overview.
Assembly is in reverse order of removal, note the following:
• Before removing pressure gauge, reduce fuel pressure by opening shut off valve while holding container in front of connection.