I have an '87 3/4 ton 4x4 Chevy. 350 TBI. I have factory dual gas tanks. The gauge is always right when I use just the right side tank. When I switch from the right tank to the left tank the fuel gauge will give me a random level. Sometimes it keeps the fuel level of the first tank. Other times it will go way past full and point downwards. And sometimes it will just read half empty or empty. My point is the stupid thing doesn't give an accurate reading after switching from one tank to the other. And I have no idea how much gas I have left (not good). Any help would be greatly appreciated.