its got a full tank right now, but it always says empty and 0 miles to empty.... any help would be great

Most likely your fuel sender. Just replaced mine on my Bonneville because had same issue. Can be very expensive to fix, both parts and labor. If you can do it yourself, buy parts on ebay, if not get a quote and be prepared for sticker shock. l was just using my trip reset and filling up when it reached a set mileage for about 2 years. Good Luck.

as with most older cars things wear out
it sounds like the sender unit at your fuel tank needs replacing but check your fuses first
goodluck

Did you turn the car OFF when fueling?? Other than that you got a ground wire off.

In the tank, there is a float, that goess, up and down, as the fuel level changes, get ready for this,.the float is sunk. the float has taking in gas, and the weight, has sunk the float too the bottom, and there for , always recording empty.Replace tank unit, or just keep track of your milege.

Mine was a ground by the fuse block, Hey try lincolnsonline.com

Sending unit in the tank has a float, probably full of gas so it stay at the bottom. When you burned half a tank of fuel, its easy to check and change