Erratic fuel gage

When I apply power, one gauge needle climbs slowly up and down in a herky-jerky fashion until reaching about half way, then falls back to the peg and stays there no matter what the tank quantity is. would the float/sender cause this or is the gauge shot.
Thanks, RJ.

Try running a temporary separate ground wire from the sender to the panel grounds/tree and not locally at the wing root. A lot of gauge/sender problems come from grounding issues. Cheap and easy enough to help diagnose the problem. Just my 2 cents....

ERATIC GUAGE

I switched the good gauge wires to the bad one. The eraticity, (is that a word) was the same so I ordered a new one.
Thanks for all the suggestions.