You want us to tell you what's wrong? but don't tell you it's the gauge? OK boys, let me say what I already said, but in a different way. A gas gauge (and the fuel sensing system in general), of all the gauges, is the most troublesome, long distance, ground dependent, tricky, delicate, difficult to diagnose gauge.... and then 12V conversion and adding voltage reducers. The gas gauge is old, the sender is old or Chinese new, the wiring is old and spliced a hundred times, the grounds are corroded or loose. If you really want to fix it, get the gauge and the sender away from the truck at least 50 feet and put them on a bench, a table or in an electrical laboratory. Get them working with new short test wires and a power supply, or see that they don't work and find out what is wrong. Calibrate them together to read empty and full and 1/2 empty or 1/2 full. Then put them back in with new wire and fabulous grounds and keep your fingers crossed. If the sender really does read 0-30 ohms, that does not tell you much except it has continuity. Does it read (register proper ohms to gauge) 1/3 when the tank is 1/3 full of gas? Does float go to or near bottom of tank? Does float go to or near top of tank? Does float leak? Are all grounds proper throughout the entire truck? How much gas is in your tank? exactly. There are many variables and the gauge never read exact anyway. Not much gauge needle or float vibration/slosh dampening used. Keep it full and drive on. Fill up every 100 miles, in my case that would be every year.(put Sta-Bil in it). Probably your Gauge is bad! oops!
