Fuel Gauge

	FUEL GAUGE The fuel gauge consists of a sending unit, located on the fuel tank, and a remote register unit (fuel gauge) mounted in the instrument cluster. The remote register unit pointer is controlled by a bimetallic arm and heating coil. The sending unit is a rheostat that varies its resistance depending on the amount of fuel in the tank. The gauge has 5 things that can go wrong to make it inoperative or erratic. Loose or broken wire from the 1" constant voltage regulator to the fuel gauge. 2. Defective fuel gauge. 3. Loose or broken wire from the fuel gauge to the fuel tank sending unit. 4. Defective fuel tank sending unit. 5.Poor ground between the fuel tank and body.
	FUEL GAUGE AND TEMPERATURE GAUGE The constant voltage regulator maintains an average value of 5.0 volts at the gauge terminals. The regulator is temperature compensated for all expected ambient (surrounding air) temperatures. If the fuel gauge indicates improperly and at the same time the temperature gauge indicates improperly and in the same direction, the constant voltage regulator could be defective, as it supplies both gauges.
This adjusts the lower limit, on other side of face is for upper limit	CONSTANT VOLTAGE REGULATOR TEST Turn the ignition switch ON. Check for voltage at the gauge feed wire (black with green band) at one of the gauges. The voltage should oscillate between zero and about 10 volts. If it does not, the constant voltage regulator is defective, or there is a short to ground between the voltage regulator and the gauges.
	Fuel Gauge Unit Test Place the ignition switch in the off position, and connect the terminals of two, series connected, flashlight cells to the gauge terminals. The 3 volts should cause the gauge to read approximately full scale. If the gauge unit is inaccurate or does not indicate, replace it with a new unit.
The early Falcon gauge is adjusted from the rear of the gauge	Fuel Sending Unit Test The sending unit can be tested by first making a gauge unit test to determine the accuracy of the instrument panel gauge. If the gauge unit is inaccurate or does not indicate, replace it with a new unit. If the gauge unit still indicates improperly or is erratic in its operation, the sending unit or wiring to the sending unit is faulty. Repair the wiring or replace the sending unit. Empty 73 Ohms Full 8-12 Ohms More info at: http://www.mustangandfords.com