88_stang_331_supercharge-dream

I know their pleeny of threads on this but could not find the answer im looking for.. plz help i really need it.. thank.. ok i have an 88gt and since i got it it did not read the gas always on full a lil past full wheater the car is off or on the gauge stays in full never moves unless i cut the power or so...anywase i figured it would be the slosh module thingy so i changed the cluster and nothing.. did the same thing.. so now i just bought a sending unit today. and installed it and hooked everything back up and whent to my car and gauge was like at half thank and open the key and fuel pump went on and gauge shot all the way up back to how it was from the begging so turned on my car and same thing fuel gauge still readin a lil past full. can someone please help me and tell me how to fix this problem.. im tried of always guessing my gas please help..

mattdel

The wire that leads from the sending unit to the gauge is being grounded out somewhere. You can do the same thing with the lead wire for the coolant temp sending unit, both gauges register ohm's in the same fashion. Ground = Full/Hot. Could be pinched in a bolt from some recent work, could be pinched and exposed somewhere near the tank due to saggy suspension. Any number of reasons, but it's your best bet to whats happening. The one for the gauge is Yellow/white.

88_stang_331_supercharge-dream

ok so yes im thinking it may be ground... so the update is this .... after running the car my gauge slowly like really slowly dropped to empty and of course my car was on empty so i was like okkk nice it started working so i went to put gas filled it up all the way opened the key and boom my gauge shot all the way up to full quick so i was like nice its working .... so the next day i drove for 4 hours on the freeway so by my 100miles gas was still reading full and no way it was full obviously so finally got to destination and today i have less than a quart of gas almost empty and my gauge is reading about half thank.. any ideas on whats going on .... it shoulds up quick when its filled but it comes down really slow when gas is running out and does not read acurately. ??????????

BabyGT

Still could be pinched/grounded/dirty connections. A little fluctuation in voltage will make gauges do all kinds of weird things.

88_stang_331_supercharge-dream

thanks ill check for that

Bfazona

Your in-tank float may be sticking. I would bet money on it, especially if you have checked your wiring already. Have you ever had the fuel pump assembly out? Be a good time to upgrade to a 190 or 255 lph fuel pump.

wydopnthrtl

When the carrier is out, spray brake cleaner on the contacting metals. Then work the swing arm 10times, respray, repeat, repeat. This will usually work for cars of this age. (just gunk built up on the parts)

88_stang_331_supercharge-dream

the part is brand new i bought it off 5.0 restro the latemodel resto.. and the thing is that i can pull the floter out and move it up and down and the gauge works just fine but once i install it back in it dont work like if it was getting stuck on the tank itself or something but i dont know what to do there????

mattdel

That is a possibility. There's a couple peaks 'n valleys in the tank that can snag the float on it's way in during assembly.