Fuel Pump: Testing and Inspection
WM 206601 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 battery charger.
2. Attach or mount a warning sign in a clearly visible position on the vehicle.
Example of warning sign for naked flames
3. Reduce fuel pump supply pressure. This procedure does not cause an entry to be made in the fault memory.
3.1. 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).
3.2. Then start the engine. The engine runs for a short time and then stops.
3.3. Insert the fuse again and install the cover.
Description of test procedure
Checking quantity delivered by fuel pump
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 vapours.
-> Attach warning sign in a clearly visible position.
Information
- The battery voltage must not fall below 12.5 volts during the fuel delivery rate check.
1. PIWIS Tester 9718 must be connected to the adapter line at the input socket in the vehicle and ignition must be switched on.
1.1. Switch off all loads, such as radio, air conditioning, etc. Switch on the Tester and select the relevant vehicle.
PIWIS Tester start page
2. Run the individual control unit search for DME. Select DME and press F12>> to start the control unit search.
Control unit search
3. Find and select the Special functions menu item. Press F12>> to continue.
Special functions menu
4. Select Drain tank in the menu and press F12>> to continue.
Draining fuel tank
5. Follow instructions on the screen. Press F12>> to continue.
Instructions for Drain tank function
6. Remove cover for rear underbody.
-> 519419 Removing and installing cover for rear underbody 519419 Removing and Installing Cover for Rear Underbody.
7. Have a measurement adapter 9705 -A- , a fuel-resistant container, a measuring cup and a stopwatch to hand for measuring.
Measurement adapter 9705
8. Loosen rapid-action coupling on the fuel supply line -1-.
Fuel lines
8.1. To do this, press the locking lugs and pull off the coupling.
8.2. Collect emerging residual fuel.
9. Connect the measurement 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).
9.1. Secure the adapter -1- to the hydraulic line with a tie-wrap -2- for example.
Securing measurement adapter with tie-wraps
9.2. Pull on the lines to check that they are secure.
10. Place the drainage hose after the pressure regulator into a petrol-resistant container. The container must be empty.
10.1. Make sure that the canister does not tip over.
Symbolic representation of tank
11. Keep a stopwatch to hand for taking measurements.
12. Start the Drain tank routine by pressing F8 Start and start the stopwatch at the same time.
Measuring time: 60 seconds!
12.1. Collect emerging fuel in a container you have to hand.
Starting Drain tank function
13. Press F8=Stop after 60 seconds to deactivate the routine.
Ending Drain tank function
14. 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.
14.1. 2.9-litre intake manifold injection engine:
=> Volume: 2200 ml
14.2. 3.4-litre DFI (direct fuel injection) engine:
=> Volume: 3300 ml
15. Remove measurement adapter 9705. Collect emerging fuel.
15.1. Place rapid-action coupling on the fuel supply line.
15.2. Make sure that the coupling is fitted correctly and securely (it must lock with an audible click).
Pull on the lines to check that they are secure.
16. Switch off ignition, switch off the PIWIS Tester and disconnect adapter line to the vehicle.
Subsequent work
1. Check that the fuel line is not leaking at the rapid-action coupling.
2. Install cover for rear underbody.
-> 519419 Removing and installing cover for rear underbody 519419 Removing and Installing Cover for Rear Underbody.
3. Disconnect and remove battery charger.
4. Remove warning sign.