Fuel Pump: Testing and Inspection

Checking Fuel Pump Delivery Pressure (S62)

Switch off ignition.
Remove rear underbody protection from assemblies.


CAUTION!
The fuel in the fuel lines is under pressure (approx. 5 bar)!
Catch and dispose of escaping fuel.


E39 only:







Release screw connections (1).
Press cover (2) downwards on left side of floor plate.

E52 only:







Remove cover (1).

E39 and E52:







Remove dust cap (1).







Connect special tool kit 13 5 220 (comprising 13 5 221 and 13 5 222) to pressure sensor of DIS Tester.
Connect pressure sensor to DIS Tester.


CAUTION!
Do not under any circumstances screw in the check valve up to the mechanical stop.
This could damage the valve in the pressure regulator housing.







Attach special tool kit 13 5 220 to housing of pressure regulator and tighten knurled nut until hand-tight.
Screw out check valve (1) so that valve in pressure regulator housing is closed.
Start engine.
Screw in check valve (1) until a pressure reading is indicated on DIS Tester.
Measuring fuel pressure.
- Select Measurement.
- Multimeter function appears
- Select Pressure test
- Read off pressure.

Compare with test pressure.
Switch off engine.

Checking fuel pump:

Remove fuel pump relay.







Connect special tool 61 3 050 to terminals 87 and 30.
Press button and read off fuel pump delivery pressure on DIS Tester.
Fuel pump delivery pressure.



NOTE:
Removing special tool kit 13 5 220:
- Switch off engine
- Screw out check valve fully again.
- Remove special tool kit 13 5 220 from pressure regulator housing.
- Catch and dispose of escaping fuel.


NOTE:
Interrogate fault memory of DME control module.
Check stored fault messages.
Rectify faults.
Then clear fault memory.