Possible causes of a dead fuel gauge (stock)???
 

My fuel gauge has been stuck on Full since I got the car. What I need to know, is if there is anything behind the dash that could be shot before I start tearing the tank off the rear....

Hey, I have the same problem with my '88GT. I was told that it could be the sending unit in the tank or the gauge itself.
Mine is actually stuck past the full mark. It's weird because sometimes it will suddenly start falling to the empty mark and have the "low fuel" light come on and then slowly work its way back to past "full"
It could be a full tank of gas and it will still do it sometimes.
I'm thinking it's probably the sending unit with mine and yours as well. I just haven't had the desire to drop the tank and mess with it yet.

Mine stays at the beyond full mark until i have like a quarter tank left then it drops. Very odd lol. Sorry i dont have an answer to your question though hehe.

Later,
Nick

My 88 GT does the same.. now its complete stuck at beyond full with no drop ever.. Its supposed to be the sending unit in the tamk.. I priced out a new one from ford at $110 .. Now its just time to drop the tank and get her in.. good luck!

im not sure if it works the same for you guys but in my 66 it all works off 1 wire to the sending unit and if that wire finds ground somewhere it will go all the way up past full. and if while driving around it comes off it will drop to zero and the fuel light will come on and then when it touches again it will go back up.. try connecting a battery and a volt meter to the sending unit before you take it out that way you can check it. not sure if its the same for the 80's mustangs but thats my .02

We've got the same problem with our 88GT - fuel gauge needed pegged past F. We dropped the gas tank and put a 190 fuel pump in. What's interesting while we had the wires disconnected with gas tank out - we turned the ignition key on to see if the fuel gauge needed dropped. Didn't move off F - so our thoughts were sending unit is fine. Rational was - if the sending unit was bad causing needle to peg - it would've dropped when the sending unit was disconnected.

My 89 had the same problem,the fuel sending units are from what I understand,basically a piece of crap,Hooked an Ohm meter up to it and found it was bad,so to my understanding you have to replace it with aftermarket or live with it,I pulled my tank and installed a fuel cell .problem solved. The Ford sending units suck and they go bad. Pulling the tank is no big deal,2 starps and the filler neck slides off,make sure the tank is near empty not a big job.good luck.

Jack
1989 LX

sending units...
 

Definitely the sending unit....
It is easy to replace.
The most common failure points are the harness connectors at the top of the sending unit housing.
When you drop the tank you will easily recognize corrosion and fraying of the wires, and in some cases a failed plastic connector.
All it takes is any moisture/corrosion on any bare wire and your guage is worthless.
I have done this repair more times than I care to talk about...

Thanx for the advice guys. I appreciate it....even though I am NOT looking forward to dropping the stoopid tank...:)

Re: sending units...
 

How much was that sending unit and where did you buy it from?

What about a resistor located behind the gauge cluster....? I've heard that can go bad as well...


Might be faster to try the $30 part than to begin tearing the tank off. GOod idea/bad idea???

a resistor sounds a whole lot easier to replace than droppin the tank again.

Free..
 

I just went to the local Ford junkyard here in Jacksonville and got one off a SN95 wreck for free. I know they wouldn't charge anyone more than ten bucks for entire unit and the harness...
They are called "Rusty Acres" and they supply Ford stuff across the Southeast...

Hey Hozer - I'm assuming you mean you got a new sending unit and wiring harness from the junkyard... Let me know if that works; as I've got the same problem.. Good luck.

when the key is off the needle drops to empty and when the key is on its pegged past full.. thats how mine is and i was told maybe it was the Ground ??? i dunno

Ours stays pegged at all times regardless of key position. I'm thinking my problem is actually the gauge itself.

I don't about that....... I think I'd rather unbolt the two straps that holf the tank up than to tear the instrument cluster apart and mess around with unhooking/rehooking that speedo cable.

That resistor in the back of the guage cluster is the slosh circuit and It went bad in my car, If you can get another one from a junk yard or know someone with and extra try that. It is there to eep the fuel guage from going crazy because the gas is sloshing around in the tank. I have seen more of those circuits go bad than guages or sending units. Just my $.02


Bobby