jeryst
Well-Known Member
Hi all, I need some advice. I bought an all original 74 Challenger Rally. The gas gauge was working. I noticed that the corner of the tank was sleeping, so I bought a new gas tank, and took it to a garage to have it installed. I had read that the new sending units are not very accurate, so I told them to use the original sending unit since it was working.
When I got the car back, the gas gauge was not working. The mechanic said that he put all the wires back as they had come off. They are saying that maybe the gauge is no good, but the gauge and wiring worked before, so I have to assume the problem is with the tank and/or sending unit because that is all that was touched.
I don't want to take it back to them and would like to do some troubleshooting of my own, but I don't have the means to remove the tank, so I am looking for suggestions as to what the problem may be. The car has somewhere between half and full tank of gas.
Disclaimer: I am a total noob concerning electronics. I've tried to read up on the issue but they keep referring to ground and resistance to ground, and my brain just seems to have problems grasping those concepts. I am assuming that the wire that connects to the sending unit goes straight to the gas gauge.
1. Could the original sending unit be incompatible with the new tank, or could it be installed incorrectly somehow?
2. The mechanic said the ring on the original sending unit is rusty, so could that be causing a ground issue?
3. Could the sending unit have broken during the switch?
4. What has to be grounded, the tank, or the sending unit, or both, or neither? I've run a ground wire to the tank, with no effect.
5. Could they have shorted out the gauge or voltage limiter when doing the install?
6. When measuring resistance, do you measure it on the post that the gauge wire attaches to? I had a friend come over with a meter, and he said there is resistance on the post that the gauge wire attaches to, but he didn't give me a number.
Thanks for any suggestions anyone can offer.
When I got the car back, the gas gauge was not working. The mechanic said that he put all the wires back as they had come off. They are saying that maybe the gauge is no good, but the gauge and wiring worked before, so I have to assume the problem is with the tank and/or sending unit because that is all that was touched.
I don't want to take it back to them and would like to do some troubleshooting of my own, but I don't have the means to remove the tank, so I am looking for suggestions as to what the problem may be. The car has somewhere between half and full tank of gas.
Disclaimer: I am a total noob concerning electronics. I've tried to read up on the issue but they keep referring to ground and resistance to ground, and my brain just seems to have problems grasping those concepts. I am assuming that the wire that connects to the sending unit goes straight to the gas gauge.
1. Could the original sending unit be incompatible with the new tank, or could it be installed incorrectly somehow?
2. The mechanic said the ring on the original sending unit is rusty, so could that be causing a ground issue?
3. Could the sending unit have broken during the switch?
4. What has to be grounded, the tank, or the sending unit, or both, or neither? I've run a ground wire to the tank, with no effect.
5. Could they have shorted out the gauge or voltage limiter when doing the install?
6. When measuring resistance, do you measure it on the post that the gauge wire attaches to? I had a friend come over with a meter, and he said there is resistance on the post that the gauge wire attaches to, but he didn't give me a number.
Thanks for any suggestions anyone can offer.