Fuel Injectors. Checking And Replacing - BMW 5251 Service Manual

Fuel injectors, checking and replacing
The fuel injectors are electronically controlled solenoid valves
that provide precisely metered and atomized fuel into the en-
gine intake ports.
The injectors receive voltage from the ECM relay. The ECM
controls the opening by activating the ground circuit forthe in-
jector valve solenoids. The ECM varies the duration (in milli-
seconds) of "opening" time to regulate the airlfuel ratio.
For a quick check of the injectors, run the engine and touch
each injector with a screwdriver or stethoscope. You should
feel a vibration or hear a buzzing
Remove fuel injection harness from injectors by unclipping
locking clip at each injector. Lift harness off injectors.
CA U J I O G
Be sure ignition is OFF before disconnecting or reconnecting
DME system components.
Use a multimeter to test injector coil resistance between in-
jector terminals.
l ~ u e l injector coil resistance
16R
at
20"
C
(68" F)
Disconnect negative (-) battery cable
C A U T I O G
Prior to disconnecting the battery, read the battery discon-
nection cautionsgiven
in
001 General Warnings and Cau-
tions.
4
Remove plastic trim plugs (arrows) and fasteners, then re.
move cover from above fuel injectors.
-
Disconnect vacuum line from fuel pressure regulator.
-
Remove wiring harness duct mounting fasteners.