ok i got a 93 f150 shortbed 4.9 liter

my gas gauge would go very far past full when i start up the truck regaurdless of how much gas i have in it

i changed the gauge cluster and it still does it

any suggestions?

 

Bad connection, open wire or bad sender.

 

my 87 is the same it will b buried past full then jump to past E my dad told me its a spring or sumthing like that in the tank will let you know when i fix mine if u havnt yet

 

Could be a bad sending unit in the tank, or any number of things , good luck on finding the problem.

Mike

 

Umm, not a bad bent or broken spring. If you have a single tank, your truck is still wired for dual tanks in the dash. There's a little blank that fills the spot for the tank switch in the bezel (black part) of the dash, just next to the headlamp switch. That little blank actually has jumpers in it to bypass the non-existant tank pump and sender. If that connector has come loose, it'll peg out your gauge, for one thing. I intentionally disconnected mine when installing a new stereo because the little plastic bosses for mounting it were cracking and I figured the weight of the wire harness was going to pull it out leaving me a nasty looking hole in the dash. I found out the hard way, completely disconnected, it will also stop the fuel pump from running. That was actually the first symptom I noticed, but the second when I looked down in dismay at a truck that wasn't running after it got new tunes, was the fuel gauge was pegged out. I knew I only had about 1/4 tank, and the gauge had ALWAYS worked before, and reasonably accurately from 1/2 tank down. It lies like a dog above 1/2, though. No way I could get 2/3 of my tank mileage in the last half tank.

Sorry for the detour, but check the wiring from that blank all the way to the sending unit. The pegged gauge suggests an open or broken wire. The gauge relies on the sending unit to pull it downscale. Pegged out past full is what happens when there's no circuit down-stream of the gauge. Could just be a corroded connection at the tank.

 

Sounds like a very common problem, Both of my 88's do the same thing. It's on the top of my to do list on the truck. From all the other posts I've read it seems that most agree on a wire problem. Good luck and keep us posted on what fixes your problem.

Merry Christmas