It has no ground for the gauge. When you loose a ground on the gauge it pegs out full. check your ground at the e-brake(most common location) or find the blk.yel wire from the sending unit and ohm it out to ground. Simple fix if you can't find the loose ground is to tie into the ground wire and attach it to a solid ground location.
I'm about to get away from work and will check back this evening when I get home to see if you were able to find the ground at the fuel sending unit..Find a meter if you dont have one . it is an invaluable tool with our jeeps.
Don't move needles ,lol that is not a good habit to get into. They are old but still sensitive and I have seen a few times where they stopped working because the pressure spring is stretched when moved by hand.
Did grounding the blk/yel wire not work?
Did you find the ground coming from the gauge cluster connection to ground under the dash?
If you have the gauge cluster out then look at the circuit card that feeds the cluster ,find the ground strip in there and follow it to the connection plug the pin it coordinates with is the ground wire. I didn't bring my manual to work today so I dont have a reference to look at now,sorry.
If you follow the ground wire to the tub then take it loose and scrap the paint til its bare metal to ensure a good ground connection from the gauge.
Not it will not go to empty aslong as there is no ground present..
No ground underneath then everything is up..
No ground connection gauge will read full(up).
What kind of shape was the circuit card in?? was there any corrosion built up on it??
Take it off of the cluster and verify you dont have any burnt spots in the traces. You may have burnt the ground trace from moisture or corrosion eating thru it..
It may take us a few things to trouble shoot before we find the problem but it will be found.
power & ground is good. so i open up the gauge, turn the needle to empty, plugged it back in & the needle went back up to full
Here you said the power and ground are good... How did you verify it?? Did you ohm out the ground wire to the chasis/tub to get continuity?
Did you read 12v across the blk/yel(-) and org/blk(+) at the sending unit?
Ohm between the blk/yel and the tan/blk(sends signal to the gas gauge) wires?
I'm just trying to see waht all you have done so far as for trouble shooting..
Ok if this is the case then the only suggestion I have from here is to drop the tank and see if the arm on the sending unit is hung up. I was hoping that wouldn't be the case cause it can be a pita sometimes.
You need to stop by parts house, lowes, home depot or such and get a $10-$15 meter. Ohm the wires to ground to verify that you absalutely have ground at gauge cluster and sending unit then proceed to dropping the tank.
Once you get the tank dropped then you can see if the sending unit arm is hanging up not allowing it to drop with the gas level. You can ohm out the sending unit as you raise and lower the arm to make sure it is good.
I think I woud like to join this thread...mine has read empty for a while now. Developed a fuel hose leak, so went ahead and dropped the tank. Replaced the fuel pump/sender with new, and new gasket. New hoses. Reinstalled and the gauge still reads empty. I have a ground indication on the gauge cluster wire? Thanks
hey man theres nothing u can do because my yj is doinng the same thing there a place behind all the gauges were the wires connect from to gauges to were ever the other wiers come from well were they connec jeep did a very por desinge they are connected somwat like takimg ur hand and putting it in a baseball glove very por connection it wiggesls and then the gauge doesnt read pissed me off when that happen cause i replace everything thAt had to do with fuel or electrical even a new harness :o