heres some test you can do to see if its the gauge or float. and if the wire is grounded it will read emty so you may have a grounded wire.

4th Gen LT1 F-body Tech Articles

 

Found and fixed the problem. When I put the pump in the tank somehow the float came off of the pump. Pulled the pump back out and reattached the float and the gauge works fine now. I did run into another problem though, the o ring in the quick connect line was damaged and looked more like a u ring instead. I had to go to the auto parts store and buy some fuel injector o rings to fix it seeing as how they didn't have any other o rings that would work. Once I got home I put in the correct size fuel injector o ring into the quick connect line, reattached the line, and no leaks. Everything has been good here now for about a week. My fuel mileage has increased as well now too. I seem to be getting about 80 more miles to the tank. This coming Tuesday I am going to reseal the hatch. I left it unsealed for a while to make sure there would be no more leaks. Thanks for all of your help.

 

Cool man. Glad it's fixed!

 

Just glad to have my car back up and running again. Felt lost without it...lol