2004 Cadillac srx 4.6 awd faulty fuel gauge. Bought the car with a bad sending unit. Would read full, then sometimes at about a quarter and occasionally while driving it would shut off and would not start again. Would throw a couple gallons in it and it would start right away, I'd get it to the gas station just for it to only take a few more gallons before going full. So, whenever the car shuts off it's never been empty, the sensor must read empty and trick the computer causing it to shut off so it doesn't burn the fuel pump out (I would assume is my guess) . Well, I replaced the fuel pump assembly that had the sending unit as well built in. Got it all in, car starts right away after priming it a few times, runs great, but fuel gauge will read half full for about a minute, then drop all the way to empty. Any suggestions on what might be going on here?