I just replaced my in-tank sending unit from one from the parts yard. I swapped out the whole assembly. The car started fine, then enroute to the gas station began to run VERY rough. I added 1/3 tank fuel and the gauge works, but I had to pump the gas and limp the car home the 3 blocks from the gas station. I'm not sure if I maybe have a bad pre-pump, or something else. Anyone know what the limp-home mode of a replaced sending unit would be? Thanks, Jamie