Mine used ta read wrong. I just dropped the tank, pulled the sending unit out, adjusted the pickup tube and float, put it all back together, and it works fine! I purposely set it a little off so the wife would quit running outa gas tho. I think I just adjusted it about an inch off of the bottom. When I fill it up, it shows almost to the full line, just a little shy of it. Close enough for me. But it sounds like you're having the same problem I had. Don't think it's the sending unit because it's running til it can't pick up anymore gas!
EZ
EZ