Fuel Gauge going past full?

[Vicinity]

My fuel gauge reads somewhere down south when I turn on the acc setting on my key. It's an autometer fuel gauge and american autowire wiring kit.



Is the sending unit bad? That's the only thing I can think of...

[77thor]

You have an OPEN circuit somewhere.
The sender should read 0 ohms for EMPTY and 90 ohms for a FULL tank.

[Vicinity]

It's doing it without the sender hooked up.

[John Wright]

~ (infinity) is an open circuit.....
0 ohms is not an open circuit, it is complete continuity....so maybe it is grounded somewhere
between the gauge and the sending unit.

[77thor]

~ (infinity) is an open circuit.....
0 ohms is not an open circuit, it is complete continuity....so maybe it is grounded somewhere
between the gauge and the sending unit.

Yes, I agree... But he stated in the title that the "Fuel gauge going past full" so it must be an OPEN circuit....

[dontlifttoshift]

It's doing it without the sender hooked up.

That's why. the gauge think there is a way full tank because you have no sender hooked up. If you ground the sender wire from the gauge it should read empty

[John Wright]

Yes, I agree... But he stated in the title that the "Fuel gauge going past full" so it must be an OPEN circuit....

LOL...wow, I need to examine my comprehension skills.....duh. Somehow I read that as going past empty. Nevermind, I'll go back to sleep now.

[Vicinity]

That's why. the gauge think there is a way full tank because you have no sender hooked up. If you ground the sender wire from the gauge it should read empty

It's doing it with both the sender attached and the sender unattached, which is why I don't understand how it's happening. So, do I ground the ground, ground the sender and 12v to the ignition wire?

The ignition and the ground wires are fine, they're all daisy chained on the back on the panel and all the other gauges are operating fine.

[dontlifttoshift]

If it does it with the sender attached make sure the gas tank is grounded, too. the sending unit grounds through the tank, in theory. I always put a separate ground wire under one of the sending unit attachment screws and run it to the frame to help eliminate inaccurate readings. Try that first.

If that doesn't work take the wire that goes from the gauge to the sender, disconnect from the sender, and then ground it. gauge should read empty at that point. If it does your gauge is probably good and you have ground issues.

Clear as mud?

Donny

[Vicinity]

Got it. I don't remember a ground on the sending unit, that could actually be it. The sending unit on my tank was beat to hell.

[Vicinity]

Yeah, not ground at the sender. The sender was also REALLY corroded. I'm just going to replace it. Couldn't hurt.

Should I get a sending unit with a return?

[dontlifttoshift]

Glad you got it nailed down.

As far as the return, I would rather have it and not need it than need it and not have it.

[John Wright]

Glad you figured it out.....I need to work on my wife's Tahoe....her gauge is reading empty but only when you fill it all the way up to the top....anything below 3/4's it seems to read fine.