Fuel Pump: Testing and Inspection

Engine

Fuel Pump Circuit Troubleshooting

Fuel Pump Circuit Troubleshooting

If you suspect a problem with the fuel pump, check that the fuel pump actually runs; when it is on, you will hear some noise if you listen to the fuel fill port with the fuel fill cap removed. The fuel pump should run for 2 seconds when the ignition switch is turned to ON (II). If the fuel pump does not make noise, check as follows:

1. Under-dash fuse/relay box internal circuit check:

Under-dash fuse/relay box internal circuit check
-1. Turn the ignition switch to LOCK (0).

-2. Remove PGM-FI main relay 2 (A) from the under-dash fuse relay box.





-3. Turn the ignition switch to ON (II).

-4. Measure the voltage between test points 1 and 2.









Is there battery voltage?
-YES- Go to step 2.
-NO-
* Replace PGM-FI main relay 1.
* If needed, replace the under-dash fuse/relay box Service and Repair.

2. Open wire check (IG1_FUEL_PUMP line):

Open wire check (IG1_FUEL_PUMP line)
-1. Measure the voltage between test points 1 and 2.









Is there battery voltage?
-YES- Go to step 3.
-NO-
* Check the No. B4 (15 A) fuse in the under-dash fuse/relay box.
* If needed, replace the under-dash fuse/relay box Service and Repair.

3. Open wire check (FUEL_PUMP_RLY_CL- line):

Open wire check (FUEL_PUMP_RLY_CL- line)
-1. Turn the ignition switch to LOCK (0).

-2. Jump the SCS line with the HDS.

-3. Disconnect the following connector.





-4. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The FUEL_PUMP_RLY_CL- wire is OK. Go to step 4.
-NO- Repair an open in the FUEL_PUMP_RLY_CL- wire between the under-dash fuse/relay box and the ECM/PCM (A40).

4. Determine possible failure area (PGM-FI main relay 2 or under-dash fuse/relay box, others):

Determine possible failure area (PGM-FI main relay 2 or under-dash fuse/relay box, others)
-1. Reinstall PGM-FI main relay 2.

-2. Connect terminals A and B with a jumper wire.









-3. Turn the ignition switch to ON (II).

-4. Measure the voltage between test points 1 and 2.









Is there battery voltage?
-YES- Go to step 6.
-NO- Go to step 5.

5. PGM-FI main relay 2 check:

PGM-FI main relay 2 check
-1. Turn the ignition switch to LOCK (0).

-2. Remove PGM-FI main relay 2 (A) from the under-dash fuse relay box.





-3. Test PGM-FI main relay 2.

Is PGM-FI main relay 2 OK?
-YES- Replace the under-dash fuse/relay box Service and Repair.
-NO- Replace PGM-FI main relay 2.

6. ECM/PCM operation check:

ECM/PCM operation check
-1. Turn the ignition switch to LOCK (0).

-2. Reconnect ECM/PCM connector A (49P).

-3. Exit the SCS mode with the HDS.

-4. Turn the ignition switch to ON (II), then measure the voltage between test points 1 and 2.









Is there battery voltage?
-YES- Update the ECM/PCM ECM/PCM Update if it does not have the latest software or substitute a known-good ECM/PCM Service and Repair, then recheck. If the symptom/indication goes away and the ECM/PCM was updated, troubleshooting is complete. If the symptom/indication goes away and the PCM was substituted, replace the original ECM/PCM Service and Repair.
-NO- Go to step 7.

7. Determine possible failure area (FUEL_PUMP_RLY_OUT line, GND line):

Determine possible failure area (FUEL_PUMP_RLY_OUT line, GND line)
-1. Turn the ignition switch to LOCK (0).

-2. Remove the access panel from the floor Fuel Tank Unit Removal/Installation.

-3. Disconnect the following connector.





-4. Turn the ignition switch to ON (II), then measure the voltage between test points 1 and 2.









Is there battery voltage?
-YES- Go to step 9.
-NO- Go to step 8.

8. Open wire check (FUEL_PUMP_RLY_OUT line):

Open wire check (FUEL_PUMP_RLY_OUT line)
-1. Turn the ignition switch to LOCK (0).

-2. Remove PGM-FI main relay 2 (A).





-3. Connect terminals A and B with a jumper wire.









-4. Measure the voltage between test points 1 and 2.









Is there battery voltage?
-YES- The FUEL_PUMP_RLY_OUT wire is OK. Replace PGM-FI main relay 2.
-NO- Repair an open in the FUEL_PUMP_RLY_OUT wire between PGM-FI main relay 2 and the fuel tank unit 4P connector.

9. Open wire check (GND line):

Open wire check (GND line)
-1. Turn the ignition switch to LOCK (0).

-2. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The GND wire is OK. Replace the fuel pump Fuel Pump/Fuel Gauge Sending Unit Removal and Installation.
-NO- Repair an open in the GND wire between the fuel tank unit 4P connector and G601.