95 fsb fuel sender testing

I have a 95 bronco 5.8 with 41k miles. I had an issue some time ago with fuel delivery. replaced fuel pump with oem pump 1 year ago. This resolved the issue. Four years ago I replaced the fuel sender and the fuel gauge was back in operation. Now, four years later, my fuel gauge was pegged over full. I set up a resistor assembly at about 70ohms. I unhooked the new harness by the tank that had to be installed with the new pump. I jumped the yellow/white and black with the resistor. My gauge showed about a half a tank. Ok, so I figured that something went bad with the sender again. I purchased a new oem sender and installed. Now my gauge shows empty. Note the gauge is not pegged below empty. So now I went back to the connector by the tank with the resistor. The gauge works. What in the hell could be going on? The gauge went from pegged over full with 4 year old sender to empty, but not pegged empty. Yes I have put gas in the truck, about 20 gallons. Also note this is a rarely used, extremly well maintained and garage stored truck. Beginning to feel like I need to drive it more.