When the fuel gauge on my 2006 Chevy diesel shows empty only about 14 gallons ar eneeded to fill it. Not much of an issue since I've only been using it around town, but now I have to make several long drives in it next month and I'd like to have an accurate readout of my fuel state. Any suggestions about how to go about fixing this (or getting it fixed in the Tulsa area) ? I'm not the original owner, I hate to think there might be something taking up room in the fuel tank.