Last year I purchased a 98 diesel and since then, the fuel gauge has been acting goofy. The dealer I purchased the truck from said that something needed to be "flashed" in order to get the gauge working right. I took the truck to my home town dealer and he informed me that "flashing" has nothing to do with the fuel gauge. He couldn't offer any advice on my problem however, offered to bring the truck in to search out the problem at full shop rate. I declined since I'm sure I can fix it myself if I could just figure out where the problem is. Here's the situation. When I fill the tank, the gauge goes all the way to empty. As soon as I get 75 to 80 miles on that tank the gauge goes all the way to full and stays there until I fill the tank again. This has the markings of reversed wiring on the sender but it seems to me that the gauge would gradually go from empty to full and not make the immediate jump up to full. Any help with this issue will be greatly appreciated.
Thanks, Kirk

The sender is shot, about $35 from the dealer. You will have to drop the tank or tilt the bed (best) to get at it though.
Instructions here http://dodgeram.org/tech/repair/fuel_sender/Huey_C-sender.htm