Subaru IMPREZA 2004 Service Manual page 376

ENGINE (DIAGNOSTICS)
Step
1 CHECK OPERATING SOUND OF FUEL
PUMP.
Make sure that fuel pump is in operation for
two seconds when turning the ignition switch to
ON.
NOTE:
Fuel pump operation can also be executed us-
ing Subaru Select Monitor.
For the procedure, refer to "Compulsory Valve
Operation Check Mode". <Ref. to
EN(H4SO)(diag)-48, Compulsory Valve Oper-
ation Check Mode.>
2 CHECK GROUND CIRCUIT OF FUEL PUMP.
1)Turn the ignition switch to OFF.
2)Remove the fuel pump access hole lid.
3)Disconnect the connector from fuel pump.
4)Measure the resistance of harness connec-
tor between fuel pump and chassis ground.
Connector & terminal
(R58) No. 4 — Chassis ground:
3 CHECK POWER SUPPLY TO FUEL PUMP.
1)Turn the ignition switch to ON.
2)Measure the voltage of power supply circuit
between fuel pump connector and chassis
ground.
Connector & terminal
(R58) No. 1 (+) — Chassis ground ( − − − − ):
4 CHECK HARNESS BETWEEN FUEL PUMP
AND FUEL PUMP RELAY CONNECTOR.
1)Turn the ignition switch to OFF.
2)Measure the resistance of harness connec-
tor between fuel pump and fuel pump relay.
Connector & terminal
(R58) No. 1 — (B46) No. 4:
5 CHECK HARNESS BETWEEN FUEL PUMP
AND FUEL PUMP RELAY CONNECTOR.
Measure the resistance of harness between
fuel pump and fuel pump relay connector.
Connector & terminal
(R58) No. 1 — Chassis ground:
Diagnostics for Engine Starting Failure
Does the fuel pump produce
operating sound?
Is the resistance less than 5
Ω?
Is the voltage more than 10 V? Replace the fuel
Is the resistance less than 1
Ω?
Is the resistance more than 1
MΩ?
EN(H4SO)(diag)-70
Check
Check fuel injec-
tor circuit. <Ref. to
EN(H4SO)(diag)-
72, FUEL INJEC-
TOR CIRCUIT,
Diagnostics for
Engine Starting
Failure.>
Go to step 3.
pump. <Ref. to
FU(H4SO)-57,
Fuel Pump.>
Go to step 5.
Go to step 6.
Yes No
Go to step 2.
Repair harness
and connector.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
fuel pump connec-
tor and chassis
grounding terminal
• Poor contact in
coupling connector
Go to step 4.
Repair harness
and connector.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
fuel pump connec-
tor and chassis
grounding terminal
• Poor contact in
coupling connec-
tors
Repair short circuit
in harness
between fuel pump
and fuel pump
relay connector.