Fuel Pump: Testing and Inspection
Checking Delivery Rate Of Electric Fuel Pump
Tools
Technical values
Preliminary work
INFORMATION: The battery voltage must not fall below 12.5 volts during the fuel delivery rate check.
1. Check the battery charge state using a voltmeter or the PIWIS Tester 9718.
1.1. Connect a charger.
2. Remove underbody covers.
2.1. Remove rear cover.
2.2. Remove centre part of middle cover.
Checking
Checking delivery rate of electric fuel pump
INFORMATION: The battery voltage must not fall below 12.5 volts during the fuel delivery rate check.
1. Attach or mount a warning sign in a clearly visible position on the vehicle.
2. Reduce fuel pump supply pressure. This procedure does not cause an entry to be made in the fault memory.
2.1. To do this, remove the cover of the fuse carrier in the left footwell and take out the fuse for the fuel pump - level D, fuse F1 (1st from left) -.
2.2. Then start the engine. The engine runs for a short time and then stops.
2.3. Insert the fuse again and replace the cover.
3. PIWIS Tester 9718 must be connected to the adapter line at the input socket in the vehicle and ignition must be switched on.
3.1. Switch off all loads, such as radio, air conditioning, etc. Switch on the Tester and select the relevant vehicle.
4. Run the individual control unit search for DME. Select DME and press F12>> to start the control unit search.
5. Find and select the Special functions menu item. Press F12>> to continue.
6. Select Drain tank in the menu and press F12>> to continue.
7. The following message is displayed.
8. Have a measurement adapter 9705, a fuel-resistant container, a measuring cup and a stopwatch to hand for measuring.
9. Open the retaining clip -1- for the fuel lines on the underbody. To do this, unclip the locking lugs -arrow-.
WARNING:
Highly inflammable or explosive materials
- Danger of fire or explosion
- Avoid contact with hot parts or sources of ignition.
- Use suction to remove ignitable vapors.
- Attach warning sign in a clearly visible position.
10. Disconnect rapid-action coupling on the fuel supply line -1- by pressing in the locking lug and pulling off the coupling. Collect emerging residual fuel with a cloth.
11. Connect the measuring adapter 9705 special tool to the fuel line using the rapid-action coupling. Make sure that the coupling is fitted correctly and securely (it must lock with an audible click).
11.1. Pull on the lines to check that they are secure.
12. Place the drainage hose after the pressure regulator into a petrol-resistant container. Make sure that the container does not tip over.
13. Have a stopwatch ready for the following measurement.
14. Start the Drain tank routine by pressing F8 Start and start the stopwatch at the same time.
Measuring time: 60 seconds.
14.1. Collect emerging fuel in a container you have to hand.
15. Press F8=Stop after 60 seconds to deactivate the routine.
16. Pour the collected fuel into the measuring cup and compare the quantity with the vehicle-specific values listed below. This gives the minimum pump rate.
16.1. Carrera 2:
Diameter: 2.80 l/min
16.2. Carrera 4:
Diameter: 2.75 l/min
17. Remove measurement adapter 9705 and attach rapid-action coupling to fuel supply line. Collect escaping fuel. Make sure that the plug-in coupling is fitted correctly (must engage audibly) by pulling the line apart.
18. Switch off ignition, switch off the PIWIS Tester and disconnect adapter line to the vehicle.
Subsequent work
1. Install underbody covers.
2. Disconnect the charger.
3. Remove warning sign.