MPI – Troubleshooting
13-37
INSPECTION PROCEDURE 25 <EVOLUTION-VI>
Fuel pump system
Probable cause
D The engine-ECU turns the fuel pump relay ON when the engine is cranking or
running, and this supplies power to drive the fuel pump.
D The engine-ECU supplies power to the fuel pump through the resistor at low load
operations. It supplies power directly to the fuel pump at high load operations
to increase the pump output.
D Malfunction of the fuel pump relay
D Malfunction of the fuel pump relay No.2
D Malfunction of the fuel pump
D Malfunction of fuel pump resistor
D Improper connector contact, open or short-circuited
harness wire
D Malfunction of engine-ECU
OK
Check the fuel pump drive control circuit.
(Refer to P.13-54, INSPECTION PROCEDURE 47.)
Check the harness wire between fuel pump
relay No.2 and fuel pump relay connector,
and repair if necessary.
NG
Repair
NG
OK
Check trouble symptom.
NG
Check the harness wire between fuel pump relay No.2 and
engine-ECU connector, and repair if necessary.
OK
Check trouble symptom.
NG
Replace the engine-ECU.
OK
Check trouble symptom.
OK
Check the following connector: B-60
NG
Repair
OK
Measure at the engine-ECU connector B-60.
D Disconnect the connector, and measure at the harness side.
D Voltage between 39 and earth
D MUT-II Actuator test: 07 Fuel pump
OK: System voltage
NG
Check the following connector: A-123
NG
Repair
NG
Check the harness wire between fuel pump resistor and fuel pump
relay connector, and repair if necessary.
OK
Measure at the fuel pump resistor connector A-124.
D Disconnect the connector, and measure at the harness side.
D Voltage between 1 and earth
D MUT-II Actuator test: 13 Fuel pump relay No.2
OK: System voltage
OK
Measure at the fuel pump relay No.2 connector A-123.
D Disconnect the connector, and measure at the harness side.
D Disconnect the fuel pump resistor connector.
D Voltage between each of 1 and 3 and earth
D MUT-II Actuator test: 07 Fuel pump drive
OK: System voltage
NG
Check the following connector: B-28
NG
Repair
OK
Check the fuel pump relay No.2 and fuel pump resistor.
(Refer to P.13-68.)
NG
Replace
OK
Check the fuel pump relay. (Refer to P.13-68.)
NG
Replace
Check the harness wire between fuel pump resistor and fuel pump
connector, and repair if necessary.
OK
Perform fuel pump operation check.
D Disconnect the fuel pump resistor connector.
D Apply system voltage to terminal No.2 of the harness side
connector.
OK: Fuel pump operates.
NG
Perform fuel pump operation check.
D Disconnect the fuel pump relay No.2 connector.
D Apply system voltage to terminal No.2 of the harness side
connector.
OK: Fuel pump operates.
NG
Check the fuel pump circuit.
(Refer to P.13-54, INSPECTION PROCEDURE 46.)
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