Fuel Pump: Testing and Inspection

Checking Quantity Delivered By Fuel Pump - Returnless Fuel System, - As Of MY 2002

WARNING: Please observe the general safety instructions when working on the fuel system and when handling petrol and other fuels.

Attach or mount a warning notice on the vehicle in a clearly visible position -see Figure-.







Sample warning notice on 996 engine compartment lid







Special tool for testing the fuel quantity

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

1. Check the charge state of the battery, e.g. using a voltmeter or the Porsche System Tester PST 2. The battery voltage must not fall below 12 volts during the check.
2. Reduce the pressure of the quantity delivered by the fuel pump. To do this, remove the cover of the fuse carrier in the left footwell and take out the fuse for the fuel pump (level C, 4th fuse from left). Then press the starter for a couple of seconds. This procedure does not cause a fault to be recorded in the fault memory. Insert the fuse again and replace the cover.
3. Connect the Porsche System Tester PST 2 in the vehicle, switch on the ignition and switch off all loads, such as radio, air conditioning, etc.
4. Remove the rear and middle underside panels. To remove the rear panel, the left side panel must also be loosened, position 4, 5 and 9.







5. Loosen the rapid-action coupling on the fuel supply line -arrow-; to do this, press in the locking lug and pull off the coupling. Collect emerging residual fuel with a cloth, for example.








6. Connect the special tool measurement adapter 9705 to the rapid-action coupling on the fuel line -see Figure-. Pay attention to the correct, secure seating of the coupling (must engage audibly), check it by pulling on the line.







7. Place the drainage hose after the pressure regulator into a petrol-resistant container. Also secure the container so that it will not fall.







8. Actuate the fuel-pump relay with the Porsche System Tester PST 2. To do this, select the line Drive links after Control units - DME individual search, then select the fuel-pump relay and activate it using the F8 key -see Figure- until fuel emerges from the drainage hose. Deactivate the fuel-pump relay using the F8 key and drain any escaping fuel from the container into a petrol-resistant container. Have a stopwatch ready for subsequent measurement.
9. Then, actuate the fuel pump again with the System Tester and keep it active for 60 seconds. Start the stopwatch at the same time. Collect emerging fuel in the container you have to hand. Deactivate the fuel-pump relay after 60 seconds.
10. Transfer the collected fuel into a suitable measuring cup.

Nominal values for the delivered fuel quantity.
- Carrera 2, all: at least 2.0 litres
- Carrera 4, Row: at least 2.1 litres
- Carrera 4, USA: at least 1.9 litres

11. Remove the special tool and attach the rapid-action coupling onto the fuel supply line. Pay attention to the correct, secure seating of the coupling (must engage audibly), check it by pulling on the line.
12. Mount the underside panels, position 4, 5 and 9.
13. Switch ignition off, and switch off and disconnect the Porsche System Tester.