FUEL LEVEL SENDER
The fuel level sender is located in the fuel tank and is used to measure the amount of fuel in the fuel tank and communicate the fuel level to the fuel gauge on the vehicle dashboard.
The fuel level sender in a vehicle’s fuel tank is actually a combination of three components; a float, an actuating rod and a resistor. The sensor assembly is often referred to as a sender. It is a relatively simple system once the function of each component part understood.
This combination of components sends a variable signal to the fuel gauge. The fuel level sender is a potentiometer that is adjusted by a float attached to a rod. When the fuel in the tank drops in level, the arm with the attached float correspondingly drops, which changes the amount of resistance in the potentiometer. It is a simple mechanism, although all the contacts must be very clean and tight since the whole system relies on resistance metering. A bad ground can cause a difference in resistance that the gauge would indicate.