2004 SUBARU FORESTER fuel pump

EN(H4DOTC 2.5)-125
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK POWER SUPPLY CIRCUIT TO FUEL
PUMP CONTROL UNIT.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from fuel pump
control unit.
3) Turn the ignition switch to ON.
4) Measure the voltage between fuel pump
control unit and chassis ground.
Connector & terminal
(R122) No. 10 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 2.Repair the power
supply circuit.
N
OTE:
In this case repair
the following:
 Open or ground
short circuit in har-
ness between fuel
pump relay and
fuel pump control
unit.
 Poor contact in
fuel pump control
unit connector.
 Poor contact in
fuel pump relay
connector.
2 CHECK GROUND CIRCUIT OF FUEL PUMP
CONTROL UNIT.
1) Turn the ignition switch to OFF.
2) Measure the resistance of harness
between fuel pump control unit and chassis
ground.
Connector & terminal
(R122) No. 5 — Chassis ground:Is the resistance less than 5
Ω?Go to step 3.Repair the harness
and connector.
NOTE:
In this case repair
the following:
 Open circuit
between fuel pump
control unit and
chassis ground.
 Poor contact in
fuel pump control
unit connector.
3 CHECK HARNESS BETWEEN FUEL PUMP
CONTROL UNIT AND FUEL PUMP CONNEC-
TOR.
1) Disconnect the connector from fuel pump.
2) Measure the resistance of harness
between fuel pump control unit and fuel pump
connector.
Connector & terminal
(R122) No. 6 — (R58) No. 4:
(R122) No. 7 — (R58) No. 1:Is the resistance less than 1
Ω?Go to step 4.Repair open circuit
between fuel pump
control unit and
fuel pump.
4 CHECK HARNESS BETWEEN FUEL PUMP
CONTROL UNIT AND FUEL PUMP CONNEC-
TOR.
Measure the resistance of harness between
fuel pump control unit and chassis ground.
Connector & terminal
(R122) No. 6 — Chassis ground:
(R122) No. 7 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 5.Repair ground
short circuit
between fuel pump
control unit and
fuel pump.
5 CHECK HARNESS BETWEEN FUEL PUMP
CONTROL UNIT AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance in harness
between fuel pump control unit and ECM con-
nector.
Connector & terminal
(R122) No. 8 — (B137) No. 28:
(R122) No. 9 — (B135) No. 27:Is the resistance less than 1
Ω?Go to step 6.Repair the harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit
between fuel pump
control unit and
ECM.
 Poor contact in
fuel pump control
unit and ECM con-
nector

EN(H4DOTC 2.5)-126
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
6 CHECK HARNESS BETWEEN FUEL PUMP
CONTROL UNIT AND ECM CONNECTOR.
Measure the resistance of harness between
fuel pump control unit and chassis ground.
Connector & terminal
(R122) No. 8 — Chassis ground:
(R122) No. 9 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 7.Repair the ground
short circuit
between fuel pump
control unit and
ECM.
7 CHECK POOR CONTACT.
Check poor contact in ECM and fuel pump
control unit connector.Is there poor contact in ECM
and fuel pump control unit con-
nector?Repair the poor
contact in ECM
and fuel pump
control unit.Go to step 8.
8 CHECK EXPERIENCE OF RUNNING OUT OF
FUEL.Did the vehicle experience run-
ning out of fuel?Finish the diagno-
sis.
N
OTE:
DTC record may
be conducted as a
result of fuel pump
idling while running
out of gas.Replace the fuel
pump control unit.
FU(H4DOTC 2.5)-
44, Fuel Pump
Control Unit.> Step Check Yes No

EN(H4DOTC 2.5)-147
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
7 CHECK FUEL TANK CORD.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from fuel sub
level sensor.
3) Measure the resistance between fuel sub
level sensor and chassis ground.
Connector & terminal
(R59) No. 1 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 8.Repair ground
short circuit in fuel
tank cord.
8 CHECK FUEL TANK CORD.
1) Disconnect the connector from fuel pump
assembly.
2) Measure the resistance between fuel pump
assembly and chassis ground.
Connector & terminal
(R59) No. 2 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 9.Repair ground
short circuit in fuel
tank cord.
9 CHECK FUEL LEVEL SENSOR.
1) Remove the fuel pump assembly. FU(H4DOTC)-62, Fuel Pump.>
2) Measure the resistance between fuel level
sensor and terminals with its float set to the full
position.
Te r m i n a l s
No. 2 — No. 3:Is the resistance 0.5 — 2.5 Ω? Go to step 10.Replace the fuel
level sensor.
10 CHECK FUEL SUB LEVEL SENSOR.
1) Remove the fuel sub level sensor. FU(H4DOTC 2.5)-55, Fuel Sub Level Sensor.>
2) Measure the resistance between fuel sub
level sensor and terminals with its float set to
the full position.
Te r m i n a l s
No. 1 — No. 2:Is the resistance 0.5 — 2.5 Ω? Repair poor con-
tact in harness
between ECM and
combination meter
connector.Replace the fuel
sub level sensor. Step Check Yes No

EN(H4DOTC 2.5)-149
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK SPEEDOMETER AND TACHOME-
TER OPERATION IN COMBINATION
METER.Does the speedometer and
tachometer operate normally?Go to step 2.Repair or replace
the combination
meter. 3, Combination
Meter System.>
2 CHECK INPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON. (engine OFF)
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B136) No. 20 (+) — Chassis ground (
−):Is the voltage more than 4.75
V?Go to step 3.Even if the malfunc-
tion indicator light
illuminates, the cir-
cuit has returned to
a normal condition
at this time. A tem-
porary poor contact
of the connector
may be the cause.
N
OTE:
In this case repair
the following:
 Poor contact in
fuel pump connec-
tor
 Poor contact in
coupling connector
3 CHECK INPUT VOLTAGE OF ECM.
1) Turn the ignition switch to OFF.
2) Disconnect the combination meter connec-
tor (i11) and ECM connector.
3) Turn the ignition switch to ON.
4) Measure the voltage of harness between
ECM and chassis ground.
Connector & terminal
(B136) No. 20 (+) — Chassis ground (
−):Is the voltage more than 4.75
V?Go to step 4.Repair battery
short circuit
between ECM and
combination meter
connector.
4 CHECK HARNESS BETWEEN ECM AND
FUEL TANK CORD.
1) Turn the ignition switch to OFF.
2) Separate fuel tank cord connector (R57)
and rear wiring harness connector (R15).
3) Measure the resistance between ECM and
fuel tank cord.
Connector & terminal
(B136) No. 20 — (R15) No. 7:Is the resistance less than 5
Ω?Go to step 5.Repair open circuit
between ECM and
fuel tank cord.
5 CHECK HARNESS BETWEEN FUEL TANK
CORD AND CHASSIS GROUND.
Measure the resistance between fuel tank cord
and chassis ground.
Connector & terminal
(R15) No. 3 — Chassis ground:Is the resistance less than 5
Ω?Go to step 6.Repair open circuit
between fuel tank
cord and chassis
ground.
N
OTE:
In this case repair
the following:
Poor contact in
coupling connector
6 CHECK FUEL TANK CORD.
1) Disconnect the connector from fuel level
sensor.
2) Measure the resistance between fuel level
sensor and coupler connector.
Connector & terminal
(R57) No. 3 — (R58) No. 5:Is the resistance less than 10
Ω?Go to step 7.Repair open circuit
between coupling
connector and fuel
level sensor.

EN(H4DOTC 2.5)-150
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
7 CHECK FUEL TANK CORD.
1) Disconnect the connector from fuel sub
level sensor.
2) Measure the resistance between fuel level
sensor and fuel sub level sensor.
Connector & terminal
(R58) No. 3 — (R59) No. 2:Is the resistance less than 10
Ω?Go to step 8.Repair open circuit
between fuel level
sensor and fuel
sub level sensor.
8 CHECK FUEL TANK CORD.
Measure the resistance between fuel sub level
sensor and coupler connector.
Connector & terminal
(R57) No. 2 — (R59) No. 1:Is the resistance less than 10
Ω?Go to step 9.Repair open circuit
between coupling
connector and fuel
sub level sensor.
9 CHECK FUEL LEVEL SENSOR.
1) Remove the fuel pump assembly.

2) While moving the fuel level sensor float up
and down, measure resistance between fuel
level sensor terminals.
Te r m i n a l s
No. 2 — No. 3:Is the resistance more than 53
Ω?Replace the fuel
level sensor. to FU(H4DOTC
2.5)-54, Fuel Level
Sensor.>Go to step 10.
10 CHECK FUEL SUB LEVEL SENSOR.
1) Remove the fuel sub level sensor. FU(H4DOTC 2.5)-55, Fuel Sub Level Sensor.>
2) While moving the fuel sub level sensor float
up and down, measure resistance between
fuel sub level sensor terminals.
Te r m i n a l s
No. 1 — No. 2:Is the resistance more than 45
Ω?Replace the fuel
sub level sensor.
FU(H4DOTC 2.5)-
55, Fuel Sub Level
Sensor.>Replace the com-
bination meter.
Combination
Meter Assembly.> Step Check Yes No

EN(H4DOTC 2.5)-258
ENGINE (DIAGNOSTIC)
General Diagnostic Table
19.General Diagnostic Table
A: INSPECTION
1. ENGINE
NOTE:
Malfunction of parts other than those listed is also possible. General.>
Symptom Problem parts
1. Engine stalls during idling.1) Electronic throttle control
2) Manifold absolute pressure sensor
3) Mass air flow and intake air temperature sensor
4) Ignition parts (*1)
5) Engine coolant temperature sensor (*2)
6) Crankshaft position sensor (*3)
7) Camshaft position sensor (*3)
8) Fuel injection parts (*4)
2. Rough idling1) Electronic throttle control
2) Manifold absolute pressure sensor
3) Mass air flow and intake air temperature sensor
4) Engine coolant temperature sensor (*2)
5) Ignition parts (*1)
6) Air intake system (*5)
7) Fuel injection parts (*4)
8) Crankshaft position sensor (*3)
9) Camshaft position sensor (*3)
10) Oxygen sensor
11) Fuel pump and fuel pump relay
3. Engine does not return to idle.1) Electronic throttle control
2) Engine coolant temperature sensor
3) Manifold absolute pressure sensor
4) Mass air flow sensor
4. Poor acceleration1) Manifold absolute pressure sensor
2) Mass air flow and intake air temperature sensor
3) Electronic throttle control
4) Fuel injection parts (*4)
5) Fuel pump and fuel pump relay
6) Engine coolant temperature sensor (*2)
7) Crankshaft position sensor (*3)
8) Camshaft position sensor (*3)
9) A/C switch and A/C cut relay
10) Engine torque control signal circuit
11) Ignition parts (*1)
5. Engine stalls or engine sags or hesitates at
acceleration.1) Manifold absolute pressure sensor
2) Mass air flow and intake air temperature sensor
3) Engine coolant temperature sensor (*2)
4) Crankshaft position sensor (*3)
5) Camshaft position sensor (*3)
6) Purge control solenoid valve
7) Fuel injection parts (*4)
8) Fuel pump and fuel pump relay
6. Surging1) Manifold absolute pressure sensor
2) Mass air flow and intake air temperature sensor
3) Engine coolant temperature sensor (*2)
4) Crankshaft position sensor (*3)
5) Camshaft position sensor (*3)
6) Fuel injection parts (*4)
7) Throttle position sensor
8) Fuel pump and fuel pump relay

EN(H4DOTC 2.5)-259
ENGINE (DIAGNOSTIC)
General Diagnostic Table
*1: Check ignition coil & ignitor ASSY 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. 7. Spark knock1) Manifold absolute pressure sensor
2) Mass air flow and intake air temperature sensor
3) Engine coolant temperature sensor
4) Knock sensor
5) Fuel injection parts (*4)
6) Fuel pump and fuel pump relay
8. After burning in exhaust system1) Manifold absolute pressure sensor
2) Mass air flow and intake air temperature sensor
3) Engine coolant temperature sensor (*2)
4) Fuel injection parts (*4)
5) Fuel pump and fuel pump relay Symptom Problem parts