Low Fuel Sensor

     At the bottom of most automotive fuel senders is a tiny cylinder, around the size of the tip of your baby finger. It has one wire going to it. That's the "low fuel" sensor. I pry that off the unit, solder a ground lead to it's exterior.  Send 12v thru a 560 ohm resistor to that sensor. When you see 8.2v, the sensor is wet. When you see 6.5v, it's dry.  12v means it's open circuit, something wrong.