1997 SUBARU LEGACY fuel pump

8F1CHECK OPERATING SOUND OF FUEL
PUMP.
Make sure that fuel pump is in operation for two seconds
when turning ignition switch to ON.
: Does fuel pump produce operating sound?
NOTE:
Fuel pump operation check can also be executed using
Subaru Select Monitor (Function mode: FD01).
For the procedure, refer to“COMPULSORY VALVE
OPERATION CHECK MODE”.
: Check fuel injector circuit.
: Go to step8F2.
OBD0132A
8F2CHECK GROUND CIRCUIT OF FUEL
PUMP.
1) Turn ignition switch to OFF.
2) Disconnect connector from fuel pump.
3) Measure resistance of harness connector between fuel
pump and chassis ground.
: Connector & terminal
(R58) No. 4—Chassis ground:
Is the resistance less than 5Ω?
: Go to step8F3.
: Repair open circuit in fuel pump ground circuit.
OBD0133A
8F3
CHECK POWER SUPPLY TO FUEL PUMP.
1) Turn ignition switch to ON.
2) Measure voltage of power supply circuit between fuel
pump connector and chassis ground.
: Connector & terminal
(R58) No. 1 (+)—Chassis ground ():
Is the voltage more than 10 V?
: Replace fuel pump.
: Go to step8F4.
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8. Diagnostics for Engine Starting Failure

B2M0526A
8F4CHECK HARNESS BETWEEN FUEL
PUMP AND FUEL PUMP RELAY CON-
NECTOR.
1) Turn ignition switch to OFF.
2) Measure resistance of harness connector between fuel
pump and fuel pump relay.
: Connector & terminal
(R58) No. 1—(B46) No. 4:
Is the resistance less than 1Ω?
: Go to next.
: Repair open circuit in harness between fuel pump
and fuel pump relay connector.
: Connector & terminal
(R58) No. 1—Chassis ground:
Is the resistance more than 1 MΩ?
: Go to step8F5.
: Repair short circuit in harness between fuel pump
and fuel pump relay connector.
G2M0461
8F5
CHECK FUEL PUMP RELAY.
1) Disconnect connectors from fuel pump relay and main
relay.
2) Remove fuel pump relay and main relay with bracket.
3) Connect battery to fuel pump relay connector terminals
No. 1 and No. 3.
4) Measure resistance between connector terminals of
fuel pump relay.
: Terminals
No. 2—No. 4:
Is the resistance less than 10Ω?
: Go to step8F6.
: Replace fuel pump relay.
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8. Diagnostics for Engine Starting Failure

B2M0527A
8F6CHECK HARNESS BETWEEN ECM AND
FUEL PUMP RELAY CONNECTOR.
1) Disconnect connectors from ECM.
2) Measure resistance of harness between ECM and fuel
pump relay connector.
: Connector & terminal
(B84) No. 32—(B46) No. 3:
Is the resistance less than 1Ω?
: Go to next.
: Repair open circuit in harness between ECM and
fuel pump relay connector.
: Is there poor contact in ECM connector?
: Repair poor contact in ECM connector.
: Check fuel injector circuit.
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8. Diagnostics for Engine Starting Failure

9. General Diagnostic Table
A: GENERAL DIAGNOSTICS TABLE WITH
NONCONFORMITY SYMPTOM FOR ENGINE
NOTE:
Malfunction of parts other than those listed is also possible.

Symptom Problem parts
1. Engine stalls during idling.1) Idle air control solenoid valve
2) Mass air flow sensor
3) Ignition parts (*1)
4) Engine coolant temperature sensor (*2)
5) Crankshaft position sensor (*3)
6) Camshaft position sensor (*3)
7) EGR valve
8) Fuel injection parts (*4)
2. Rough idling1) Idle air control solenoid valve
2) Mass air flow sensor
3) Engine coolant temperature sensor (*2)
4) Ignition parts (*1)
5) Air intake system (*5)
6) Fuel injection parts (*4)
7) Throttle position sensor
8) Crankshaft position sensor (*3)
9) Camshaft position sensor (*3)
10) EGR valve
11) Oxygen sensor
12) Fuel pump and fuel pump relay
3. Engine does not return to idle.1) Idle air control solenoid valve
2) Engine coolant temperature sensor
3) Accelerator cable (*6)
4) Throttle position sensor
5) Mass air flow sensor
4. Poor acceleration1) Mass air flow sensor
2) Throttle position sensor
3) Fuel injection parts (*4)
4) Fuel pump and fuel pump relay
5) Engine coolant temperature sensor (*2)
6) Crankshaft position sensor (*3)
7) Camshaft position sensor (*3)
8) A/C switch and A/C cut relay
9) Engine torque control signal circuit
10) Ignition parts (*1)
5. Engine stalls or engine sags or hesitates at
acceleration.1) Mass air flow sensor
2) Engine coolant temperature sensor (*2)
3) Crankshaft position sensor (*3)
4) Camshaft position sensor (*3)
5) Purge control solenoid valve
6) EGR valve
7) Fuel injection parts (*4)
8) Throttle position sensor
9) Fuel pump and fuel pump relay
6. Surge1) Mass air flow sensor
2) Engine coolant temperature sensor (*2)
3) Crankshaft position sensor (*3)
4) Camshaft position sensor (*3)
5) EGR valve
6) Fuel injection parts (*4)
7) Throttle position sensor
8) Fuel pump and fuel pump relay
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9. General Diagnostic Table

Symptom Problem parts
7. Spark knock1) Mass air flow sensor
2) Engine coolant temperature sensor
3) Knock sensor
4) Fuel injection parts (*4)
5) Fuel pump and fuel pump relay
8. After burning in exhaust system1) Mass air flow sensor
2) Engine coolant temperature sensor (*2)
3) Fuel injection parts (*4)
4) Fuel pump and fuel pump relay
*1: Check ignitor, ignition coil and spark plug.
*2: Indicate the symptom occurring only in cold temperatures.
*3: Ensure the secure installation.
*4: Check fuel injector, fuel pressure regulator and fuel filter.
*5: Inspect air leak in air intake system.
*6: Adjust accelerator cable.
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9. General Diagnostic Table

OBD0240
T: DTC P0170
—FUEL TRIM MALFUNCTION—
DTC DETECTING CONDITION:

Two consecutive driving cycles with fault
TROUBLE SYMPTOM:

Erroneous idling

Engine stalls.

Poor driving performance
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODE.

10T1
CHECK EXHAUST SYSTEM.
: Are there holes or loose bolts on exhaust
system?
: Repair exhaust system.
: Go to step10T2.
10T2
CHECK AIR INTAKE SYSTEM.
: Are there holes, loose bolts or disconnec-
tion of hose on air intake system?
: Repair air intake system.
: Go to step10T3.
G2M0340
10T3
CHECK FUEL PRESSURE.
1) Release fuel pressure.
(1) Remove fuel pump access hole lid located on the
right rear of trunk compartment floor (Sedan) or lug-
gage compartment floor (Wagon).
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10. Diagnostic Chart with Trouble Code for LHD Vehicles

B2M0047
(2) Disconnect connector from fuel tank.
(3) Start the engine, and run it until it stalls.
(4) After stopping the engine, crank the engine for 5 to
7 seconds to reduce fuel pressure.
(5) Turn ignition switch to OFF.
B2M0047
2) Connect connector to fuel tank.
OBD0711
3) Disconnect fuel delivery hose from fuel filter, and con-
nect fuel pressure gauge.
G2M0348
4) Start the engine and idle while gear position is neutral.
5) Measure fuel pressure while disconnecting pressure
regulator vacuum hose from intake manifold.
: Is fuel pressure between 226 and 275 kPa
(2.3—2.8 kg/cm2,33—40 psi)?
: Go to next step 6).
: Repair the following items.
Fuel pressure too high
Clogged fuel return line or bent
hose
Fuel pressure too low
Improper fuel pump discharge

Clogged fuel supply line
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10. Diagnostic Chart with Trouble Code for LHD Vehicles

6) After connecting pressure regulator vacuum hose, mea-
sure fuel pressure.
: Is fuel pressure between 157 and 206 kPa
(1.6—2.1 kg/cm2,23—30 psi)?
: Go to step10T4.
: Repair the following items.
Fuel pressure too high
Faulty pressure regulator

Clogged fuel return line or bent
hose
Fuel pressure too low
Faulty pressure regulator

Improper fuel pump discharge

Clogged fuel supply line
WARNING:
Before removing fuel pressure gauge, release fuel
pressure.
NOTE:

If fuel pressure does not increase, squeeze fuel return
hose 2 to 3 times, then measure fuel pressure again.

If out of specification as measured at this step, check or
replace pressure regulator and pressure regulator vacuum
hose.
OBD0145A
10T4CHECK ENGINE COOLANT TEMPERA-
TURE SENSOR.
DTC P0117 [T10I0].>
1) Turn ignition switch to OFF.
2) Connect the Subaru Select Monitor or the OBD-II gen-
eral scan tool to data link connector.
3) Start the engine and warm-up completely.
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10. Diagnostic Chart with Trouble Code for LHD Vehicles