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 5P connector terminal No. 3 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 5P 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.Connect PGM-FI main relay 2 5P connector terminal No. 5 to body ground with a jumper wire.

 

9.Wait 10 seconds.

10.Connect the ECM test harness and test pin box between the ECM and connectors.

11.Check for continuity between test pin box terminal No. 89 and body ground.

Is there continuity?


YES - Go to 12.


NO - Repair open in the wire between the PGM-FI main relay 2 and ECM connector No. 4 terminal No. 8 (test pin box terminal No. 89).n


12.Reinstall the PGM-FI main relay 2.

13.Turn the ignition switch ON (II).

14.Measure voltage between pin box terminal No. 89 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.Turn the ignition switch ON (II), and measure voltage between pin box ternimal No.89 and body ground.

Is there battery voltage?


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


NO - Go to 17.


17.Turn the ignition switch OFF.

18.Remove the access panel from the floor.

19.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 26.


NO - Go to 20.


20.Turn the ignition switch OFF.

21.Remove the driver's side under cover.

22.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.

 


23.Connect the PGM-FI main relay 2 5P connector terminals No. 1 and No. 2 with a jumper wire.

 

24.Turn the ignition switch ON (II).

25.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


26.Turn the ignition switch OFF.

27.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