It could be your floater, to be honest I really dont know much about your problem. I know my cars fuel guage is not that great. Ill fill the car up and once it gets past a quarter of the way it drops a lot faster. As for the light, I have never seen mine. I am a college student and I cut it pretty close when having to put more gas it in and I never see the light on. I also noticed with my car the tank does not completley fill up when the pump stops so I let it sit for a bit and fill it back up. i.e. One day I filled the car the pump stop and so I started driving and it still needed about a quarter of gas left. Also the gauge moves very slow when moving back up after putting gas in it. I hope I helped if even a little, im sure someone knows a lot more than me.