Fuel gauge help

my fuel gauge registers between empty and 1/4 no matter the amount of fuel in the tank. I grounded the wire at the sending unit and the gauge went to full, checked the sending unit and got a reading of around 48 ohms (which as I understand it should be about a half tank. Tried running a ground from the sending unit to the chassis and got nothing still registers at the same point. If I understand everything correctly (which I likely dont) the first test says the gauge and everything there is good while the second tells me the sending unit should be good. where do I go from here?