trying to get my fuel gauge working correctly have a 555E shuttle no cab, needle moves up to bottom of the red with power and bounces in the red when moving. I have half a tank of diesel, 12 volts going to gauge and 5 volts at the tank hot wire. A new sending unit is $200. seems like maybe the float is not floating? any ideas, also anyone know of a cross reference for a sending unit if in fact that is what is bad? e with shutlle shift and no cab, gauge moves up to bottom of red
At a half tank the sending unit should read approximately 129 ohms. You might try taking it out of the tank and cleaning it then measure the resistance range while it's out. If the float is not floating you could probably find something to replace it with. I've not had mine out so I don't know if it's a brass float or a cork style. Sometimes the brass ones get a hole and fill up and sometimes the cork style become saturated. OR it could just be dirty contacts. Mine wasn't working when I got it and it just turned out to be a bad connection in the wire at the sending unit.
Take the wire off the sender, the gauge should go to one end, connect the wire to ground, the gauge should go the other end. If that works, then take the sender out and carefully wipe the crud off the wires of the rheostat, flammable brake cleaner should work good with a rag.