Fuel gauge finally works, but only briefly

I went through something like this last year and it turned out that the float had gas inside of it although no hole could be found. The sender was new but the float was very thin walled so I replaced the float with one for a Mustang which had a thick wall. Problem solved. One other thing to watch out for is the float hanging up on the fuel pickup tube not allowing the float to rise past the tube. That was another problem that I encountered when resolving a fuel gauge issue.