Don't that drive you nuts! Every time I fill up, mine tells me "low fuel", then the gauge will fly back up, and the light goes out. I don't trust it, and won't let it get below a half tank.
Well, I walked out without getting it fixed. I didn't like the guy's attitude at the shop. He said there is no fuse that controls the gas gauge, and that it'd be $82... An hour's labor, just to find out what the problem with it is. I walked out. I think it's worth $100 to fix it, but not $100 to diagnose it, and another $100 or more to fix it.
We're gonna take it to my dad's mechanic next time we switch trucks. Someone we can trust to not just name the biggest number they think the blond will pay.