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 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 10.


NO - Go to 6.


6.Turn the ignition switch OFF.

7.Disconnect the under-hood fuse/relay box 10P connector.

8.Turn the ignition switch ON (II).

9.Measure voltage between under-hood fuse/relay box 10P connector terminal No. 5 and body ground.

 

Is there battery voltage?


YES - Repair open in the wire between the under-hood fuse/relay box and the under-dash fuse/relay box.n


NO -

  • Replace  PGM-FI main relay 1 (C).n
  • If needed, replace the under-hood fuse/relay box.n

10.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 11.


NO -

  • Check the No. 2 FUEL PUMP (15 A) fuse in the under-dash fuse/relay box.n
  • If needed, replace the under-dash fuse/relay box.n

11.Turn the ignition switch OFF.

12.Connect PGM-FI main relay 2 (FUEL PUMP) 4P connector terminal No. 4 to body ground with a jumper wire.

 

13.Jump the SCS line with the HDS.

14.Disconnect ECM/PCM connector A (44P).

15.Check for continuity between body ground and ECM/PCM connector terminal A15.

 

Is there continuity?


YES - Go to 16.


NO - Repair open in the wire between PGM-FI main relay 2 (FUEL PUMP) and the ECM/PCM (A15).n


16.Remove the under-dash fuse/relay box, then reinstall PGM-FI main relay 2 (FUEL PUMP).

17.Reinstall the under-dash fuse/relay box.

18.Connect ECM/PCM connector terminal A6 to body ground with a jumper wire.

 

19.Turn the ignition switch ON (II).

20.Measure voltage between ECM/PCM connector terminal A15 and body ground.

 

Is there battery voltage?


YES - Go to 21.


NO - Replace  PGM-FI main relay 2 (FUEL PUMP).n


21.Turn the ignition switch OFF.

22.Reconnect ECM/PCM connector A (44P).

23.Open the SCS line with the HDS.

24.Turn the ignition switch OFF.

25.Turn the ignition switch ON (II), and measure voltage between under-dash fuse/relay box 34P connector terminal No. 10 and body ground within 2 seconds.

 

Is there battery voltage?


YES - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM, then go to 26.


NO - If needed, replace the under-dash fuse/relay box, then go to 26.


26.Turn the ignition switch OFF.

27.Remove the rear-seat cushion.

28.Remove the rear floor upper cross-member, then remove the access panel from the floor.

29.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 34.


NO - Go to 30.


30.Turn the ignition switch OFF.

31.Remove PGM-FI main relay 2 (FUEL PUMP).

32.Connect PGM-FI main relay 2 (FUEL PUMP) 4P connector terminals No. 1 and No. 2 with a jumper wire.

 

33.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).n


NO - Repair open in the wire between PGM-FI main relay 2 (FUEL PUMP) and the fuel tank unit 4P connector.n


34.Turn the ignition switch OFF.

35.Check for continuity between fuel tank unit 4P connector terminal No. 4 and body ground.

 

Is there continuity?


YES - Replace the fuel pump.n


NO - Repair open in the wire between the fuel tank unit 4P connector and G601.n