Fuel Pump Fuse And Relay; Operating Fuel Pump For Tests - BMW 5251 Service Manual

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Fuel
Tank and
Fuel
Pump
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Fuel pump fuse and relay
Troubleshooting of any fuel pump fault should begin with
checking the fuel pump fuse and the fuel pump relay. The
DME main relay should also be checked. The fuel pump relay
is located behind right side luggage compartment interior
panel.
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Fuel pump
relay
BLU =blue
ERN = blo$,m
GRN =groan
GRY = grsy
ORG =orange
PNI< =pink
RED =red
VIO =violel
WHT = wlilte
rk-;
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1
ECM
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31
8
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NOTE-
Special tools are required for some of the tests described
here.
4
Fuel pump circu~t is fuse-protected.
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6-cylinder models with Siemens DME MS41 . I , MS42, V-8
models with Bosch DME M5.2, M5.2.1 englne manage-
ment: Fuse F54,15A (luggage compartment fuse panel)
6-cylinder models with Siemens DME MS43 engine man-
agement: Fuse F22,25A (glove compartment fuse panel)
V-8 models with Bosch DME M7.2: Fuse F54,25A (lug-
gage compartment fuse panel)
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Fuse 31 in glove compartment fuse panel supplies power to
coil side of fuel pump relay. Engine control module (ECM)
supplies switched ground to relay. During starting, fuel pump
runs as long as ignition switch is in START position and con-
tinues to run once engine starts. If electrical system fault in-
terrupts power to fuel pump, engine will not run.
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Operating fuel pump for tests
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To operate fuel pump for testing purposes without having to
run engine, bypass fuel pump relay to power pump directly.
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To run fuel pump, open luggage compartment and release
right side trim panel.