fuel gauge wiring

[beakerztoyz]

I fired up my car for the first time in a long time last night, anyways the fuel gauge is messed up somehow it always reads overfull when the powers on. it doesnt have that much gas in it we tested the wires in the trunk where the ones coming up from the tank join with the ones going to the front with a testlight, and somehow when we had the wires together and were testing with the light the gauge started reading acurately, took light out it went back up to overfull

anyone got any ideas on how to fix this or whats causing it?

trying one last time to get this car street legal so shit like this has to work asap thanks

[spencerforhire]

The gauge works as a variable ground; you could be missing the ground wire if that was the one you touched with the test light. Or if you touch the tan gauge wire with it, that will bring it down too. Open circuit, gauge goes up past full. Shorted yo ground or empty, the gauge goes down.

[beakerztoyz]

Thanks Spencer, so if i follow you correctly you think it's not grounded?

[spencerforhire]

Could be, but then the fuel pump probably wouldn't run. Try again with the test light and see which wire makes it go down.

[beakerztoyz]

ok thanks man I will recheck it, I didn't think to post in my first question that i am not running the in tank fuel pump, i have a holley electric one wired up externally.. on edit it is the tan wire i am hitting with the test light that is making it go down, so i am thinking that means its a short between that connector in the trunk and the tank ??

[beakerztoyz]

Just to update this, thanks to the wiring diagrams posted on this site i was able to trace the problem to an unhooked ground wire under the dash, i hooked it up and now the gauge works.. also thanks to Spencerforhire for the advice