Fuel Pump: Testing and Inspection
Engine
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:
-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 Under-Dash Fuse/Relay Box Removal and Installation.
2. 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 Under-Dash Fuse/Relay Box Removal and Installation.
3. 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 PCM (A40).
4. 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:
-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 Testing and Inspection.
Is PGM-FI main relay 2 OK?
-YES- Replace the under-dash fuse/relay box Under-Dash Fuse/Relay Box Removal and Installation.
-NO- Replace PGM-FI main relay 2.
6. PCM operation check:
-1. Turn the ignition switch to LOCK (0).
-2. Reconnect 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 PCM PCM Update if it does not have the latest software or substitute a known-good PCM Service and Repair, then recheck. If the symptom/indication goes away and the PCM was updated, troubleshooting is complete. If the symptom/indication goes away and the PCM was substituted, replace the original PCM Service and Repair.
-NO- Go to step 7.
7. 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):
-1. Turn the ignition switch to LOCK (0).
-2. Remove PGM-FI main relay 2 (A) from the under-dash fuse relay box.
-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):
-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 Tank Unit Removal/Installation.
-NO- Repair an open in the GND wire between the fuel tank unit 4P connector and G603.