Fuel Heater: Description and Operation

This cold weather device is installed on some 1981 and 1983---84 vehicles. This thermostatically controlled fuel heater reduces the possibility of wax plugging the filter when temperatures are below 20°F. Battery voltage is directed to the heater whenever the ignition is in the ``Run'' position.
The heater consists of a strip spiral wound around the fuel pipe and a bimetal thermal switch which closes and completes the circuit when fuel temperatures are approximately 20°F. When fuel temperatures reach 50°F the thermal switch opens and deactivates the circuit.
The fuel tank filter sock is equipped with a bypass valve which opens when the filter is covered with wax, allowing fuel to flow to the heater.