Quote Originally Posted by jshifti33 View Post
I had this exact same problem. I too thought that the sending unit was bad. Luckily, before I purchased a new sending unit I decided remove the fuel pump. When I got into it I found that fuel pump o-ring had been replaced by someone who didn't know what they were doing. The o-ring had fallen out of place and was holding the float down making my gauge read empty. After, replacing the o-ring the right way the check engine light went away and my fuel gauge worked.

However, if your gauge is reading full all the time then it is probably the sending unit.

You can test if it is the fuel pump o-ring like mine was by simply filling the tank. If you notice that fuel leaks out just before the gas pump clicks off you have a bad o-ring not a bad sending unit.

If it is not your o-ring it still may not be the sending unit. On the float arm there are metal contacts that tell the computer how much gas is left in the tank. Sometimes these can get corroded. If this is the case simply clean it with a pink eraser.

Hope this helps you.
Thank for the info, to tell you exactly what mine is doing. It says its full then as your driving it will dramatically drop to empty and sit there for a bit and it may float up to either half or else it will read that it is completely full again. And this happened like 2 years ago but it resolved itself since I was to lazy to fix and since I knew how far I could go on a full tank I wasn't to concerned about running out of fuel.