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 first turned on. If the fuel pump does not make noise, check as follows:

1. Turn the ignition switch OFF.
2. Remove the glove box (see GLOVE BOX REMOVAL/INSTALLATION ), then remove the PGM-FI main relay 2.
   Fig 1: Removing PGM-FI Main Relay 2 & Glove Box

   
3. Turn the ignition switch ON (II).
4. Measure voltage between the PGM-FI main relay 2 4P connector terminal No. 4 and body ground.
   Fig 2: Measuring Voltage Between PGM-FI Main Relay 2 4-Pin Connector Terminal No. 4 & Body Ground

   

   Is there battery voltage? 

   1. YES  - Go to step 5.
   2. NO  - Repair open in the wire between the PGM-FI main relay 1 and the PGM-FI main relay 2.
5. Measure voltage between the PGM-FI main relay 2 4P connector terminal No. 1 and body ground.
   Fig 3: Measuring Voltage Between PGM-FI Main Relay 2 4-Pin Connector Terminal No. 1 & Body Ground

   

   Is there battery voltage? 

   1. YES  - Go to step 6.
   2. NO  - Repair open in the wire between the under dash fuse/relay box and PGM-FI main relay 2.
6. Turn the ignition switch OFF.
7. Disconnect ECM/PCM connector E (31P).
8. Check for continuity between the PGM-FI main relay 2 4P connector terminal No. 3 and ECM/PCM connector terminal E1.
   Fig 4: Checking Continuity Between PGM-FI Main Relay 2 4-Pin Connector Terminal No. 3 & ECM/PCM Connector Terminal E1

   

   Is there continuity? 

   1. YES  - Go to step 9.
   2. NO  - Repair open in the wire between the PGM-FI main relay 2 and the ECM/PCM (E1).
9. Reinstall the PGM-FI main relay 2.
10. Turn the ignition switch ON (II).
11. Measure voltage between ECM/PCM connector terminal E1 and body ground.
    Fig 5: Measuring Voltage Between ECM/PCM Connector Terminal E1 & Body Ground

    

    Is there battery voltage? 

    1. YES  - Go to step 12.
    2. NO  - Replace the PGM-FI main relay 2.
12. Turn the ignition switch OFF.
13. Reconnect ECM/PCM connector E (31P).
14. Turn the ignition switch ON (II), and measure voltage between ECM/PCM connector terminal E1 and body ground within the first 2 seconds after the ignition switch was turned ON (II).
    Fig 6: Measuring Voltage Between ECM/PCM Connector Terminal E1 & Body Ground

    

    Is there battery voltage? 

    1. YES  - Reprogram the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM REPROGRAMMING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
    2. NO  - Go to step 15.
15. Turn the ignition switch OFF.
16. Remove the rear seat cushion.
17. Remove the access panel from the floor.
18. Measure voltage between the fuel pump 5P connector terminal No. 5 and body ground within the first 2 seconds after the ignition switch was turned ON (II).
    Fig 7: Measuring Voltage Between Fuel Pump 5-Pin Connector Terminal No. 5 & Body Ground

    

    Is there battery voltage? 

    1. YES  - Go to step  24 .
    2. NO  - Go to step 19.
19. Turn the ignition switch OFF.
20. Remove the PGM-FI main relay 2.
21. Connect the PGM-FI main relay 2 4P connector terminals No. 1 and No. 2 with a jumper wire.
    Fig 8: Connecting PGM-FI Main Relay 2 4-Pin Connector Terminals No. 1 & No. 2

    
22. Turn the ignition switch ON (II).
23. Measure voltage between the fuel pump 5P connector terminal No. 5 and body ground within the first 2 seconds after the ignition switch was turned ON (II).
    Fig 9: Measuring Voltage Between Fuel Pump 5-Pin Connector Terminal No. 5 & Body Ground

    

    Is there battery voltage? 

    1. YES  - Replace the PGM-FI main relay 2.
    2. NO  - Repair open in the wire between the PGM-FI main relay 2 and the fuel pump 5P connector.
24. Turn the ignition switch OFF.
25. Check for continuity between the fuel pump 5P connector terminal No. 4 and body ground.
    Fig 10: Checking Continuity Between Fuel Pump 5-Pin Connector Terminal No. 4 & Body Ground

    

    Is there continuity? 

    1. YES  - Replace the fuel pump.
    2. NO  - Repair open in the wire between the fuel pump 5P connector and G551.