Metro L3-61 1.0L (1990)
Fuel Gauge: Description and Operation
The fuel gauge system consists of a sending unit, instrument voltage regulator and an electric fuel gauge. The sending unit is a variable resistor that is
controlled by a float. Corresponding to actual fuel level, the float will rise or fall. When the ignition is turned to the On position, voltage is applied to the
gauge through the voltage regulator, completing the gauge ground circuit through the sending unit.
When the tank is full and the float is raised, maximum resistance (approximately 90 ohms) is produced by the sending unit, current flow through the
gauge is decreased, and the gauge pointer moves slightly. As the tank empties and the float drops resistance in the sending unit decreases, current flow
through the gauge increases and the gauge pointer moves toward empty.
Most analog fuel gauges are of the free floating type, which means that the gauge pointer does not remain against the full stop when the ignition is off.
Rather, the pointer floats to a mid-position when no voltage is applied to the gauge.
