Fuel Gauge

The fuel gauge is operated by two intersecting coils wound around a permanent magnet rotor, and a bucking coil in series with the full coil. When voltage is applied to the coils, a magnetic field is generated. The magnetic field causes the rotor to rotate and the gauge needle to move. The magnetic fields are controlled by the fuel gauge sending unit in the fuel tank. The resistance in the sending unit varies, current through the gauge coils changes. The gauge needle moves according to the changing magnetic field. When the ignition is turned to OFF, the gauge remains at the last reading until the ignition is again turned to RUN.