Fuel Gauge Question

[Kona]

So my old gauge does not work, it was stuck on 3/4 no matter how much fuel in it, so replaced the gauge and same, replaced the cluster with a 90xj full gauges and tach and still shows empty even do the tank is full!, disconnected the sending unit and turned the key and the fuel gauge goes up past full to the max, reconnect and back to empty, already cleaned the c101 connector, checked ground and even tapped on the sending unit to maybe loosen the floater and nothing! Any other ideas? Other than the obvious which is replacing the sending unit that is hard to find ! Any help will be welcome!

[jimoshel]

Remove the sending unit, pump assembly from the tank. There are several tests you can make but the simplest is to simply move the float arm up and down, with the ign on, and watch the gauge. There is enough wiring you can hold the pump assy. outside of the edge of the Jeep and see the gauge while you move the float.

[Kona]

I'll do try that once I use some fuel! :-)

[johnj92131]

I strongly suspect you have a bad ground (s) somewhare. It is a frequent Jeep issue. Search for "ground" and I think you will get some leads. Jeeps are well known for electrical gramlins. Sorry I could not be more help. I still have ground issues with my Comanche. My 96 VW Passat is also famous for ground issues.

[Kona]

Is there a way to bypass and do a direct ground from the FSU to chassis?

[Kona]

Anyone have a sending unit? : )

[Larry 43]

I will mention this tor what it is worth. My 98 Wrangler would stick at half tank so I ran out of gas a couple of times. I put carb cleaner in the gas tank and drove it on a trail ride. after going up a steep hill a couple of times it started working again. So I put carb/injector cleaner in it periodically didn't have any more trouble with it. Still have a new sending unit in my garage that I had bought. I reasoned that it was rust or debris on the sending unit restricting the movement and the solvent loosened it with the motion of the gas. I found this quite by accident...so you can try the simple trick and maybe it will work.

[Eagle]

I don't think you have a bad ground.

 

All the gauges in the Renix cluster are energized by sensors with a range of 0 to 88 ohms. Zero ohms (no resistance) is empty -- 88 ohms (max resistance) is full. Disconnecting the sender creates an infinite (very high) resistance, which would peg the gauge. Yours does that. A bad ground would create an open circuit, and that would do the same thing -- the gauge would read full all the time. If the gauge reads empty, the circuit is sensing zero ohms (no resistance). That's either a bad sender, or a short circuit in the wiring.

[Kona]

Great! Thanks eagle! That's what I was needing the ohms! I'll test that tomorrow!

[Kona]

BTW, where or is there a fuse or relay that controls the sending unit?

[88mjgilley]

also when swaping in newer clusters i ran into a issue with one that the + and - were reversed so when my jeep was full it read empty and empty read full that may be your issue if your float or something else in your sending unit isnt messed up

[Kona]

Well, finally I was able to pull the sending unit out of the tank, the gauge works fine when moving the floater manually, so some pb blast, moved it up and down a few times, placed back in and ......... I HAVE A WORKING FUEL GAUGE!!!! Yeepeeeee!!!!!! Thanks y'all for the advices!