Greetings!

I'm having an issue with my fuel gauge. I just recently bought the car and the first thing I did upon driving it home was fill it up. I live three miles away from the gas station, and it took all of that time just to move to the top, and even so, the needle swayed back and forth between 3/4 and full. I originally thought the problem would be the fuel tank sending unit, so i got another one from a junkyard and threw it in, but it didn't affect a thing. I initially just thought this might be the way it is, but then sometimes while i'm driving, I'll notice the needle is on 1/4 when I have a full tank! this can't be right. I'm wondering if anyone else has had this problem... perhaps I need to replace the gauge?

My alternator is bad, but I don't see how that could have much to do with it, I just wanted to add that little bit of information.

Any information would be helpful, thank you =]
Frank