Fuel Gauge: Description and Operation

WARNING: Do not smoke while working on the fuel system. Keep open flame away from the work area. Drain fuel only into an approved container.

When the ignition switch is in ON (II) or START (III), battery voltage is supplied through fuse 1 to the gauges in the gauge assembly. The gauge circuit is grounded at G404.

The fuel gauge has two intersecting coils wound around a permanent magnet rotor. Voltage applied to the coils, through fuse 1, generates a magnetic field. The magnetic field, controlled by the fuel gauge sending unit, causes the rotor to rotate and the gauge needle to move. As the resistance in the sending unit varies, current through the gauge coils changes, pulling the gauge needle toward the coil with the stronger magnetic field.
The resistance of the sending unit for the fuel gauge varies from about 2-5 ohms at full, to about 110 ohms at empty. When you turn the ignition switch to LOCK (0), the gauge remains at the last reading until you turn the ignition switch to ON (II) or START (III) again.