Component Tests and General Diagnostics

Checking Fuel Pressure

Tools

Tools:

Checking fuel pressure

NOTE: The battery voltage must not fall below 12 volts during the fuel pressure check.

1. Check the battery charging condition e.g. using a voltmeter or the Porsche PIWIS Tester. The battery voltage must not fall below 12 volts during the check.







DANGER:
Risk of fire from escaping fuel.
- Danger of fatal injury and damage to property.
- Observe basic safety instructions when working on the fuel system.
- Secure working area.

2. Attach or mount a warning sign in a clearly visible position on the vehicle.
3. Relieve the fuel pressure. Testing and Inspection







DANGER:
Risk of fire from escaping fuel.
- Danger of fatal injury and damage to property.
- Observe basic safety instructions when working on the fuel system.
- Secure working area.

4. Release metal cap on test connection at fuel collection pipe and screw it off by hand (a/f 13 mm). Collect emerging fuel with a cloth.







5. Connecting cable 9559 must be connected using the pressure gauge 378a (union nut a/f 17).







6. Tighten the knurled union nuts of the connecting cable by hand on the test connection of the fuel collection pipe -Arrow-.

Procedure when engine is not running:

7. Connect the Porsche PIWIS Tester PIWIS Tester 9718 to the input socket in the vehicle using the adapter lead and switch on the ignition. Switch on the Tester and select the vehicle (option: Diagnostics).







8. Run the individual control unit search for DME using the Porsche PIWIS Tester. To do this, select DME with the tracer pen and press "F12 >>".







9. Once the individual control unit search for DME is complete, select the Drive links item, then select the fuel pump relay and activate it by pressing "F8 - Start".







10. Read value on pressure gauge. Fuel pressure - engine not running: 3.8 bar ± 0.2 bar







11. Deactivate the fuel pump relay on the PIWIS Tester by pressing "F8 - Stop". Then, press "F11 <<" to return to the start screen and switch off the Tester.
12. Switch off the ignition and remove PIWIS Tester adapter lead in the vehicle.
13. To check the engine at idle speed: pressure gauge 378a must be connected as described above. Then start the engine. Switch off the engine after reading the fuel pressure. Fuel pressure - idle speed: 3.8 bar ± 0.2 bar.
14. Loosen the union nut on the connecting cable 9559 for the pressure gauge 378a on the test connection and remove special tool. Collect emerging fuel with a cloth.

NOTE: Use the brass cap on the test connection of the fuel supply line only once as the sealing ring cannot be replaced. To avoid possible leaks, the cap must be replaced after removal.

15. Position new closure cap on test connection and tighten (a/f 13 mm). Tightening torque: 2.5 (2 ft.lb.) Nm ± 0.5 (0.5 ft.lb.) Nm