6 replies to this topic

[Ryan Wellman]

Some wires under the dash got melted together during some welding work and I've been battling with some electrical issues since. I've re-spliced all the wires that were shorted together (brake light, fuel sender, and fuel pump wires), but still have some issues that I can't diagnose. The fuel gauge does not work anymore and the fuel pump turns on and stays on when the ignition is on. I'm pretty sure that the fuel pump is only supposed to turn on the when the F/P is shorted at the diagnostic connector, can someone confirm? The fuel gauge also goes straight to empty (all the way to left beyond empty) and I know there is more than half a tank in there. My gauge has been relocated, so I can manually move the needle to full, but as soon as I turn the ignition on it quickly moves back to empty. I've even pulled the sending unit and manually moved the float and the gauge still says empty.

Any suggestions? Do I need to try a new sending unit? Or are there more wiring issues that I haven't been able to find?

[Mike Collins]

Call Wheeler, ask what he will charge you to let you talk to Brian, its worth the money!!!

[davew]

I told Brian what was wrong with your car, I just let him pull the dash apart!!!! I am management ;-)

If your gauge goes to empty, you have an open circuit/broken wire between the gauge and the tank

I know you don't want to do this, BUT!!!! I would replace the harness completely. Over the my 25 years as a mechanic, I have tried to fix enough melted harnesses to have learned not to bother fixing them. Unless you are experienced with automotive wiring AND lucky, you will be chasing problems forever.

I have wired a couple dozen GT and Formula cars to have learned that it is sometimes better to just start all over, than to try to patch together a wiring harness. Remeber wires don't go bad, connections do.

Dave

[dmathias]

Maybe too obvious of a question, but did you check the fuses under the dash. There is a fuse for the instrument panel and the fuel guage is on that circuit.

[Qik Nip]

The fuel gauge does not work anymore and the fuel pump turns on and stays on when the ignition is on. I'm pretty sure that the fuel pump is only supposed to turn on the when the F/P is shorted at the diagnostic connector, can someone confirm?

Ryan:
The fuel pump will also run if the air flow meter door is open. Are you sure it's not?
Rick

[Bench Racer]

The fuel gauge does not work anymore and the fuel pump turns on and stays on when the ignition is on. I'm pretty sure that the fuel pump is only supposed to turn on the when the F/P is shorted at the diagnostic connector, can someone confirm? Any suggestions? Do I need to try a new sending unit? Or are there more wiring issues that I haven't been able to find?

This would be a bit of testing for the fuel pump.

With the 1.6 there is a two solenoid relay under the dash above the steering column. There is also a relay under the hood on psss side in fuse box. Forgetting about the F/P jumper for now two different items energize each solenoid of the two solenoid relay which powers the fuel pump. Turing the key to "on" will energize one of the solenoids to start the fuel pump. After the car starts & with the AFM trap door open there is a switch in the AFM that closes energizing the second solenoid of the two solenoid relay. I believe the solenoid that is energized by the key is timed for some number of seconds. I tested the relays per the Haynes manual. You can do a simple test of the relays using a finger to touch the solenoids, then turn the key "on" (finger should feel a small thump) & open the flapper in the AFM (finger should feel a small thump) independent of each other. If you have not been messing around inside the AFM do not change anything in the AFM.

[ndrewoods]

Some wires under the dash got melted together during some welding work and I've been battling with some electrical issues since. I've re-spliced all the wires that were shorted together (brake light, fuel sender, and fuel pump assembly wires), but still have some issues that I can't diagnose. The fuel gauge does not work anymore and the fuel pump turns on and stays on when the ignition is on. I'm pretty sure that the fuel pump is only supposed to turn on the when the F/P is shorted at the diagnostic connector, can someone confirm? The fuel gauge also goes straight to empty (all the way to left beyond empty) and I know there is more than half a tank in there. My gauge has been relocated, so I can manually move the needle to full, but as soon as I turn the ignition on it quickly moves back to empty. I've even pulled the sending unit and manually moved the float and the gauge still says empty.

Any suggestions? Do I need to try a new sending unit? Or are there more wiring issues that I haven't been able to find?

Couldn't agree more with Dave. You would really need to change the hole wiring harness on your fuel gauge and fuel pump. Also check the fuse. Good day.