DIAGNOSTICS
SERVICE MANUAL NUMBER 24
Chart A-5 (1 of 2): Fuel System Electrical Test
FUEL PUMP
RELAY FUSE
15A
TO
SYSTEM
RELAY
902 RED
339 PNK/BLK
OR PNK
ECM
MEFI 1
MEFI 2
MEFI 3
J1-23
87a
30
85
86
87
FUEL
PUMP
RELAY
J2-9
465 DK GRN/WHT
150 BLK
450 BLK/WHT
OR BLK
120 GRY
A
M
B
FUEL PUMP
CIRCUIT DESCRIPTION
The fuel system circuit receives a supply voltage from the system relay CKT 902. The fuel
system is protected by a 15 amp fuse. After the fuse, supply voltage is delivered by CKT 339
to fuel pump relay terminal “30.” The fuel pump relay is turned on by the ECM by supplying
voltage to CKT 465. The fuel pump relay will remain ON as long as the engine is running
or cranking and the ECM is receiving reference pulses. If no reference pulses are present,
the ECM de-energizes the fuel pump relay within 2 seconds after the ignition is turned ON
or the engine is stopped.
DIAGNOSTIC AIDS
An intermittent may be caused by a poor connection, rubbed through wire insulation or a
wire broken inside the insulation. Check for the following items:
•
•
Poor connection or damaged harness. Inspect the ECM harness and connectors for
improper mating, broken locks, improperly formed or damaged terminals, poor termi-
nal to wire connections and damaged harness.
Contaminated or dirty fuel may cause the fuel pump to seize, which will cause the
fuel pump relay fuse to fail.
Index
Page 5G-34
90-861327--1 OCTOBER 1999
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 305 CID, Mercury MerCruiser 350 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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