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 driver's side under cover.

3.Remove the relay holder (A) from the under-dash fuse/relay box, and remove the PGM-FI main relay 2 (blue) (B) from the relay holder (A), after reinstall the relay holder (A) to the under-dash fuse/relay box.

 


4.Turn the ignition switch ON (II).

5.Measure voltage between the PGM-FI main relay 2 4P connector terminal No. 4 and body ground.

 

Is there battery voltage?


YES - Go to 6.


NO - Repair open in the wire between the PGM-FI main relay 1 and the PGM-FI main relay 2.n

6.Measure voltage between the PGM-FI main relay 2 4P connector terminal No. 1 and body ground.

 

Is there battery voltage?


YES - Go to 7.


NO - Repair open in the wire between the under-dash fuse/ relay box and PGM-FI main relay 2.n


7.Turn the ignition switch OFF.

8.Disconnect the negative cable from the battery.

9.Disconnect ECM/PCM connector E (31P).

10.Check for continuity between the PGM-FI main relay 2 4P connector terminal No. 3 and ECM/PCM connector terminal E1.

 

Is there continuity?


YES - Go to 11.


NO - Repair open in the wire between the PGM-FI main relay 2 and the ECM/PCM (E1).n

11.Reinstall the PGM-FI main relay 2.

12.Reconnect the negative cable from the battery.

13.Turn the ignition switch ON (II).

14.Measure voltage between ECM/PCM connector terminal E1 and body ground.

 

Is there battery voltage?


YES - Go to 15.


NO - Replace the PGM-FI main relay 2.n


15.Turn the ignition switch OFF.

16.Disconnect the negative cable from the battery.

17.Reconnect ECM/PCM connector E (31P).

18.Reconnect the negative cable from the battery.

19.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).

 

Is there battery voltage?


YES - Substitute a known-good ECM/PCM and recheck. If symptom/indication goes away, replace the original  ECM/ PCM.n


NO - Go to 20.

20.Turn the ignition switch OFF.

21.Remove the access panel from the floor.

22.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).

 

Is there battery voltage?


YES - Go to 29.


NO - Go to 23.


23.Turn the ignition switch OFF.

24.Remove the driver's side under cover.

25.Remove the relay holder (A) from the under-dash fuse/relay box, and remove the PGM-FI main relay 2 (blue) (B) from the relay holder (A), after reinstall the relay holder (A) to the under-dash fuse/relay box.

 

26.Connect the PGM-FI main relay 2 4P connector terminals No. 1 and No. 2 with a jumper wire.

 

27.Turn the ignition switch ON (II).

28.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).

 

Is there battery voltage?


YES - Replace the PGM-FI main relay 2.n


NO - Repair open in the wire between the PGM-FI main relay 2 and the fuel pump 5P connector.n


29.Turn the ignition switch OFF.

30.Check for continuity between the fuel pump 5P 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 pump 5P connector and G402.n