Fuel Pressure: Testing and Inspection

Checking Delivery Pressure Of Fuel Pump (M73)

Switch off ignition.







Rotate screws through 90°.
Remove cover from cylinder head cover.







1. Return (black fuel line)
2. Feed (light fuel line)







Open holder (1).







Cut through fuel hose (2) (feed) roughly in middle of hose. Install T-piece for fuel pressure measurement.


CAUTION!
The fuel in the fuel lines is under pressure (approx. 3 bar)!
Catch and dispose of escaping fuel.


Installation:
Replace fuel line and hose clips.







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 with quick-release coupling).
Connect special tool 13 6 051 with quick-release coupling to pressure sensor (1) of DIS Tester.







Version, fuel hoses with integrated unlocking facility:
1. Fuel feed line
2. Fuel return line


CAUTION!
The fuel in the fuel lines is under pressure (approx. 3 bar)!
Catch and dispose of escaping fuel.







Press fuel feed line (1) downwards and keep pressed.







Press unlocking ring (2) upwards, keep pressed and detach fuel feed line (1).

Installation:
Coat O-ring for assembly with anti-friction agent.







Connect special tool 13 5 270 to open pipe neck and to detached fuel feed line (shown here on M62 engine).


Connect DIS Tester.
Select "Measurement". Multimeter function appears.
Select "Pressure test".
Connect pressure sensor adapter of DIS Tester to fuel feed line.
Connect pressure sensor to DIS Tester.


CAUTION!
When removing special tool, bear in mind that fuel in fuel lines is under pressure (approx. 3 bar)!
Catch and dispose of escaping fuel.







Alternative measurement procedures:
Connect special tool 13 3 064 to fuel delivery line.
Connect special tool 13 3 060 to special tool 13 3 064.







Fold right side trim in trunk to one side. The relay bracket is installed above the battery.







Remove fuel pump relay (2).
Check whether fuel pump no longer starts up during engine starting procedure. Engine fails to start.







Connect special tool 61 3 050 to terminal (87 or 87b) and terminal (30).
Actuate button for approx. 10 seconds and read off delivery
pressure on pressure gauge.
Fuel pressure regulator,







Keep special tool 13 3 010 available for further tests.
Further procedure for checks,
Information on fuel pressure check.


NOTE:
Interrogate fault memory of DME control unit.
Check stored fault messages.
Rectify faults.
Now clear the fault memory.