Originally Posted by jmarksdragster

The sending unit is a variable resistor. As it goes up and down the resistance changes. If you hit a bad spot with no connection it will make the gauge jump. Funny you mention fall off... that is what mine did. I hear it rattling in the tank when the fuel level is low. I keep track by watching my mileage and filling up at 500 miles. Be ready to spend $200 to $500. I would leave it alone till it gets worse. I may be crawling under mine next week....