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)
• Connector Test Set (V.A.G 1594C)
• Remote Control (V.A.G 1348/3A) with Remote Control (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.
Fuel Pressure, Checking
- Remove rear seat bench.
- Remove the locking flange cover - arrows -.
- Disconnect electrical harness connector - 1 - at locking flange.
• Ignore - 2 -.
- Connect the (V.A.G 1348/3A) with (V.A.G 1348/3-3) with an adapter cable from the (V.A.G 1594C) at terminal - 1 -.
- Using insulating tape, tape over the second terminal on the (V.A.G 1348/3-3) - arrow - to prevent a short circuit.
- Connect terminal - 5 - to the vehicle ground using a jumper cable from the (V.A.G 1594C).
- Connect the (V.A.G 1348/3A) to item - A - in the terminal box in the plenum chamber (battery positive). For safety reasons, install a fuse (10 A) in the wiring connection.
- Route (V.A.G 1348/3A) switch forward in engine compartment.
- Remove the seal - arrow -.
- Unclip the plenum chamber cover - 2 - and remove it.
• Ignore - 1 and 3 -.
- Release the retainer - arrow A - and open the cover - arrow B -.
- Connect the (V.A.G 1348/3A) to item - A - in the terminal box in the plenum chamber (battery positive). For safety reasons, install a fuse (10 A) in the wiring connection.
- Remove fuel filler cap from fuel filler tube.
- Remove the front engine cover.
- Remove the fuel supply line - arrow - from the high pressure pump.
There is a risk of injury because the fuel is under high pressure.
• To reduce pressure in fuel system, lay a clean cloth around the connector and carefully loosen connector.
- Connect the (V.A.G 1318) to the fuel supply line using an adapter.
- 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 direction of flow.
- 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.
Residual Pressure, Checking
- 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 3.75 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.
• Check the fuel pump delivery quantity.
• Replace the fuel filter with the integrated fuel pressure regulator.
• Fuel pump check-valve is faulty.
Assembly is performed in the reverse order of removal, noting the following:
- Switch off ignition.
• Before removing pressure gauge, release fuel pressure by opening shut-off valve. Hold a container under the connection.
- Connect the fuel supply line - arrow - to the high pressure pump.
• Check fuel system for leaks.