drivingshadow

I have a question about my h22. My mechanic and I finished doing a shell swap from a rusted eg to a better one and we cant remember which wire is the ground wire for the fuel pump because the ECU isn't telling the fuel pump to turn on and I need my car before work on thursday. Its an OBD1 93 Eg coupe. The fuel pump works because we can mainly turn it on. The thermostat is grounded and we changed out the main relay and checked all the fuses. We also added another ground wire to the trans because we thought maybe that was it. We know its not a bad ECU because we trued another ECU and it wont turn om either. Could anyone help please

NotARaCist

iTrader: (1)

What wiring harness are you using?

drivingshadow

the one from a 93 civic dx eg coupe

tech8

Your post is not entirely clear. You seem to be mentioning two separate things. Is the issue you can't remember the location of the ground wire that should be directly wired to the fuel pump? Or is the issue the ECU is not sending the ground signal to the main relay; so, power is not going to the fuel pump?

1. The ground wire for the fuel pump itself is normally located at the driver’s door sill area on a '93.

2. Power (+) to the fuel pump is supplied by the main relay after the ECM sends a ground signal (-) to energize one of the main relay coils to close the relay contacts to allow power through to the fuel pump.

drivingshadow

oh my fault the ecu isnt sending the ground signal to the main relay so power isn't going to the fuel pump

tech8

The following must be present in order for the ECM to send the ground signal (Yel/Grn wires at ECM pins A7 and A8) to the main relay so that relay coil is energized to allow power (+) via the Yel/Grn wire to the fuel pump.

1) Power (+) to main relay and ECM:
In START, power from under-dash Fuse No. 18 (7.5A) via the Blk/Wht wires to both the main relay and the ECM (pin B9).
In RUN or START, power from under-dash Fuse No. 12 (15A)(Civic w/o SRS) via the Blk/Yel wire to the main relay
At all times, power from under-hood Fuse No. 31 (15A) via the Yel/Wht wire to the main relay.

In RUN or START, power from the main relay via the Yel/Blk wires to the ECM (pin B1 and A25).

Check the above fuses and for power (+) at the respective wires listed to the main relay and ECM. -- You may have to backprobe some of the wires at the main relay to see if power (+) is present.

2) Ground from G101 (located at thermostat housing) via one black wire to main relay and various separate ground wires branched from G101 to ECM.

3) Properly working main relay

4) Properly working ECM