2 years ago I bought a 35th Anni that had been in storage for 8 years with 87k on it. The gas gauge always showed full. Last spring the dash died so I had it repaired (power supply). The gas gauge started working except it would stay on full for about 200 miles and drop to 1/2 when empty. We found out the hard way. This spring it seems to be working perfectly. Could it be the 10% ethanol that all the gas has in it now that cleaned up the gauge while it sat in storage all this past winter. I love when things fix themselves.
I plan on replacing the pump, level sensor, filter and injectors this summer just because it is 21 years old!!

More than likely the float arm was stuck/rusted after sitting for so long. After you driving it, and running some real fuel thru the tank, it prolly freed it up.

I'm having a similar rpoblem with my 86' coupe.  It sat all winter with a full tank of gas.  I drove it  a bit this spring and when the fuel gage said it was at the 1/2 mark I filled it up.  It took over 14 gallons, it was nearer to less than 1/4 full!  I was advised to run a bottle of Techron through this tank and the next.  It has been suggested that the new fuels have a higher Sulfer content that tends to cause things like the level float to stick.  The Techron is supposed to clean this up.  I'll keep you posted on the results.

Mine (95) is getting hinky also, although I drive it alot.  Reads full for over 100 miles after a fill up, before it moves.  On the list of things to do/replace.   

I put in a bottle of Techron over a month ago, but, I haven't been able to get much driving in.  Only put on about a hundred miles since then.  The gage has moved though so that a good sign.  I'll keep you posted on the results, but it will take a while for me to go through a tank of gas. 

if you can get it by you, try the lucas cleaner. it is awesome and you can feel the difference in a short distance. i wait until the tank is low and put in a little more than what they say and run the car a bit and then fill the tank up. can usually feel the difference in the first 20-25 miles of driving. just my experience and hope it helps.

I use SeaFoam regularly in all my toys, ....EFI boat, truck, cars, 4wheelers ect...

I also will make a batch of rocket fuel and run that through all toys too.


Keeping fresh fuel is kinda hard (on stored cars), but its nothing to move the car enough to keep the fuel level sensors pliable.




Jim