Fuel

The fuel gauge sending unit is mounted on the top surface of the fuel tank. The fuel level sender itself consists of the following two components:
^ A float that rides on the surface of the fuel in the tank
^ A variable resistor that is controlled by the float arm

When electric power is supplied to the fuel gauge, current flows through the gauge to the variable resistor and then to a ground. The position of the gauge pointer is determined by the strength of the current that is flowing through the gauge.
If the tank is full, the following situations occur:
^ The resistance of the variable resistor is high (90 Ohm).
^ The current flow through the gauge is minimum.
^ The pointer indicates that the gauge reads full (F) on the gauge dial.

If the fuel level is low, the following situations occur:
^ The resistance of the variable resistor is low.
^ The current flow through the gauge is high.
^ The pointer indicates a low fuel level reading.

Intermediate fuel levels cause the pointer to indicate the corresponding position between F and E.