It seems to work fine until I get down to under a quarter tank and then the needle bounces all over the place. It seems like it corresponds to when I turn either left or right or go over bumps, but ultimately the long and short is that it is completely unreliable once I get that low on fuel.
The sender in the tank is getting worn. To fix it do a search on fuel gauge problem or something like that. Someone has goten a part # that you order through either gmpartsdirect.com or rockauto.com etc. You have to access the fuel pump through the gas tank access cover which is in the trunk. You replace just the sender unit or whatever you would call it. It is a reostat type device that you snap in to replace the worn one.
The part number is 15824379 -- HARNESS (I paid $24.90); let me did around for the thread on the replacement.. Most time consuming is getting that d*** ring off with a rubber mallet to remove the sending unit.
Ya mines also doing the same thing. About an 8th of a tank itll shoot all the way up to full and stay there until I have 5 miles left, then it will shoot down to below empty and you can see the needle go from E to below E. Thats the next thing on my list to do to my car, engine problems first...sigh