Fuel Pump: Testing and Inspection
Fuel Pump Circuit TroubleshootingIf 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 under-dash fuse/relay box, then remove PGM-FI main relay 2 (FUEL PUMP) (A) from the under-dash fuse/relay box.
3. Reinstall the under-dash fuse/relay box.
4. Turn the ignition switch ON (II).
5. Measure voltage between PGM-FI main relay 2 (FUEL PUMP) 4P connector terminal No. 3 and body ground.
Is there battery voltage?
YES - Go to step 12.
NO - Go to step 6.
6. Turn the ignition switch OFF.
7. Disconnect the under-hood fuse/relay box 10P connector.
8. Disconnect the engine wire harness 23P connector C101.
9. Disconnect the under-dash fuse/relay box 21P connector G.
10. Connect under-dash fuse/relay box 21P connector G terminal No. 4 to body ground with a jumper wire.
11. Check for continuity between under-hood fuse/relay box 10P connector E terminal No. 5 and body ground.
Is there continuity?
YES -
- Replace PGM-FI main relay 1 C.
- If needed, replace the under-hood fuse/relay box.
NO - Repair open in the wire between the under-hood fuse/relay box and the under-dash fuse/relay box.
12. Measure voltage between PGM-FI main relay 2 (FUEL PUMP) 4P connector terminal No. 1 and body ground.
Is there battery voltage?
YES - Go to step 13.
N0 -
- Check the No. 2 FUEL PUMP (15 A) fuse in the under-dash fuse/relay box.
- If needed, replace the under-dash fuse/relay box.
13. Turn the ignition switch OFF.
14. Connect PGM-FI main relay 2 (FUEL PUMP) 4P connector terminal No. 4 to body ground with a jumper wire.
15. Jump the SCS line with the HDS.
16. Disconnect ECM connector A (44P).
17. Check for continuity between body ground and ECM connector terminal A15.
Is there continuity?
YES - Go to step 18.
NO - Repair open in the wire between PGM-FI main relay 2 (FUEL PUMP) and the ECM (A15).
18. Remove the under-dash fuse/relay box, then reinstall PGM-FI main relay 2 (FUEL PUMP).
19. Reinstall the under-dash fuse/relay box.
20. Connect ECM connector terminal A6to body ground with a jumper wire.
21. Turn the ignition switch ON (II).
22. Measure voltage between ECM connector terminal A15 and body ground.
Is there battery voltage?
YES - Go to step 23.
NO - Replace PGM-FI main relay 2 (FUEL PUMP)
23. Turn the ignition switch OFF.
24. Reconnect ECM connector A (44P).
25. Open the SCS line with the HDS.
26. Turn the ignition switch OFF.
27. Turn the ignition switch ON (II), and measure voltage between under-dash fuse/relay box 34P connector F terminal No. 10 and body ground within 2 seconds.
Is there battery voltage?
YES - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.
NO - Go to step 28.
28. Turn the ignition switch ON (II), and measure voltage between under-dash fuse/relay box 34P connector F terminal No. 10 and body ground after 2 seconds.
Is there battery voltage?
YES - Go to step 29.
NO - If needed, replace the under-dash fuse/relay box, then go to STEP 29.
29. Turn the ignition switch OFF.
30. Remove the rear cushion
31. Remove the rear floor upper cross-member, then remove the access panel from the floor.
32. Turn the ignition switch ON (II), and measure voltage between fuel tank unit 4P connector terminal No. 2 and body ground within 2 seconds.
Is there battery voltage?
YES - Go to step 37.
NO - Go to step 33.
33. Turn the ignition switch OFF.
34. Remove PGM-FI main relay 2 (FUEL PUMP).
35. Connect PGM-FI main relay 2 (FUEL PUMP) 4P connector terminals No. 1 and No. 2 with a jumper wire.
36. Turn the ignition switch ON (II), and measure voltage between fuel tank unit 4P connector terminal No. 2 and body ground within 2 seconds.
Is there battery voltage?
YES - Replace PGM-FI main relay 2 (FUEL PUMP).
NO - Repair open in the wire between PGM-FI main relay 2 (FUEL PUMP) and the fuel tank unit 4P connector.
37. Turn the ignition switch OFF.
38. Check for continuity between fuel tank unit 4P connector terminal No. 4 and body ground.
Is there continuity?
YES - Replace the fuel pump.
NO - Repair open in the wire between the fuel tank unit 4P connector and G601.