Fuel Pump: Testing and Inspection

- Switch off ignition.




- Twist screws through 90°.
- Remove cover from cylinder head cover.


CAUTION: Fuel in lines is under pressure (approx. 3 bar): catch escaping fuel and dispose of correctly!





- Cut through hose to fuel delivery line (1).

Installation Note: Replace fuel hose and hose clips.

- Connect up Diagnosis Information System (DIS):
- Select Measuring option.
- Select Pressure Check.




- Install special tool 13 6 057 (T-piece) between the two open ends of the fuel delivery hose.
- Connect special tool 13 6 057 (T-piece) to Special tool 13 6 055 (reducer) and special tool 13 6 051 (hose).
- Connect special tool 13 6 051 to quick-release coupling on pressure sensor (1) on DIS.

CAUTION: Note when removing the special tool! Fuel in lines is under pressure (approx. 3 bar), catch escaping fuel and dispose of it correctly!







- Remove fuel pump relay (1).
- Connect special tool 61 3 050 to terminal 87 or 87b and to terminal 30.
- Actuate special tool 61 3 050 for approx. 10 seconds and read off delivery pressure.

NOMINAL VALUES:
Delivery pressure of fuel pump: 3 bar.
Fuel pressure regulator (testing pressure): 3.5 +/- 0.02 bar.




If delivery pressure is not reached, fuel return line must be sealed using special tool 13 3 010.
- Repeat the pressure check.

If the delivery pressure is reached or exceeded:
- Replace the pressure regulator.

If the delivery pressure is not achieved:
- Check hose routing from tank to engine on fuel pump (e.g. squashed areas, leaking).
- Check fuel filter (e.g. for contamination) and replace if necessary.

If the hose routing and fuel filter are O.K., check plug connection on the fuel pump for signs of corrosion, cleaning if necessary, then repeat the pressure test. If the delivery pressure is still not reached after this action is taken, replace the fuel pump.