Hi
my 72 chevelle has been sittting at a slight angle,engine higher than tail, for about a week. i came home started it and the gas gauge went to the tip top of full. i know it has only a few gallons in it before i left, unless the gas gods came by lol. im hoping this can be fixed by me filling the tank up with gas. i have been out of town alot on a job so i havent filled it up yet to see if this fixes it.
before this incident the gauge has always worked fine, anyone else ever had this failure? problem? im dreading the removal of the tank already! lol.

the float in my truck sticks every time i don't use it regularly... with my 77 chevy, pulling the tank will really suck... so i am just putting it off till i take the bed off my truck... i know it is the sending unit not the gauge... because the wire melted on the exhaust once and it pegged the gauge while i was driving... once i figured it out and fixed the wire, it returned to normal. but because of gas prices, i haven't daily driven my truck in 2 years... so i fill up every time i take the truck out... roughly once a month... just to make sure i got enough gas to drive... filling the tank might help free up the float, but it may be just the start of batteling the sending unit.

Ah yes, the days when you could test electrical stuff without having to visit the tool truck for another scanner adapter... My fuel gauge test was unhook the wire to the fuel sender and see if the gauge goes past full (like yours sounds like it has). Then ground the same wire, and see if the gauge goes to empty. Have the area well ventilated when you're doing this. If the gauge does this, then you've got a sender problem for sure. Have you checked the tank sender ground?

Doc here,

Good Info OGMT..

Also one other possibility exists, that is that something has cut the sender wire going back to the gauge, and it's open, you can continuity check that to be sure it is good all the way.

If you think the Float may be stuck..Go to a local Jenny Craig, bait the tailgate with Chocolate and Entice a few "Fat Bottomed Girls" To jump up and down on the rear bumper While you watch the gauge, depending on the amount it is stuck..and the enthusiasm on the Fat Bottomed Girls you may be able to dislodge it..

I just hate to see somebody go to all that work without having exhausted all other fixes first..

If it does stick sometimes, you might want to plan some time to pull the tank and replace the sender and inspect for something in there it may be hitting..Like the neighbor's Kid's Barney Action figure..

Doc

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Dropping a gas tank in a shop on a rack with a transmission jack and a couple of extra guys around is no big deal, but doing it on the floor sucks. That was the idea behind checking the dash gauge first. You're right Doc, the wire could be cut. The fact that the gauge was past full was what had me wondering about the gauge. Wonder if the harness inside the car along the floor could be damaged? I just don't remember seeing any stuck or sticking floats back then, except for if the float somehow got tangled up with the tank sock, or if the float just didn't float any more (both usually read empty). A gauge reading past full was almost always an open circuit somewhere between the gauge and the sender. Printed circuits and those goofy clips that connected the circuit to the pins on the back of the gauge act up sometimes too. But do the sender wire test and that should give you some idea of what's going on.