Fuel guage not working

[Rengo]

I just replaced the entire dash cluster in my car. Before: no speedometer, no dash lights, bad light switch and fuel gauge did not work. After: Everything except the fuel gauge works.
Does this have a wire that hooks into the back of the cluster on it? I didn't see one on the cluster I took out. Could it be a blown fuse or a short or something to do with gas tank? my dad looked at all of the fuses in the car and said that they were all ok, I do intend on replacing all of the fuses though.

 

[440Ken]

If the car is a Mopar from the 60's or 70's it has a constant voltage regulator under the dash...they go bad freguently causing the gas gauge malfunction.

 

[TrailBeast]

Does the temp gauge work?
If so, chk the ground strap at the tank sending unit.
It is a metal strap that goes from the sending unit to the steel line that is grounded to the frame.

 

[wjajr]

Depending on year of your car, voltage limiter may be housed in the gas gage.

As someone previously said sending unit in tank needs to have a good ground/ There should be a steel strip that clips to the metal snout of sending unit, and jumps over rubber fuel line coupling to clip onto metal fuel line.

One quick test is to disconnect fuel gage lead at tank, and ground it on a good ground. Have a friend observe gage for movement to full. If gage responds to grounding, than problem is a poor ground at sending unit.

 

[Otateral]

If you have a multimeter, check the ohms at the sending unit and again closer to the gauge. (Mine was a dark blue wire that runs along the drivers side.

For what its worth, when I did the test mentioned earlier, the gauge slowly went to full so I figured bad ground or bad sending unit. However, even with a new sender it did not work. The gauge was simply not reading it properly. An aftermarket gauge worked fine.

 

[RedFish]

You dont have to crawl under the car yet. You can check the sender signal at a harness connector behind the left kick panel or pierce the wire casing inside the trunk.

 

[cudajim]

If your temperature gauge works properly you can rule out the regulator in the dash, it's probably working. The regulator is wired to both the gas gauge and the temperature gauge. If it is working you need to crawl under the car, pull the wire off the sending unit and ground it (with a jumper) temporarily while your buddy looks at the gas gauge with the key on. If it moves to full scale then your problem is probably at the sending unit inside the tank or possibly the ground strap on the sending unit. You can then check the resistance of the sending unit with your ohmmeter by taking the wire off it and see what it reads. (one probe on the sender unit and the other on ground). It should read between 10 and 70 ohms, if not the unit is bad.