See Figure 4-19. The purpose of the heater is to heat fuel, so that the filter does not plug with parafin wax crystals. This will allow the use of fuels at temperatures substantially below the cloud point of the fuel.
The heater is electrically powered from the ignition circuit 39. It is placed in the filter inlet passage in the filter base.
The heater is thermostatically controlled to work when waxing of the fuel is expected. It is self-protected (by thermal feedback from the heating element to the bimetal actuator) against overheating resulting from the lack of fuel flow. Because it is located within the filter base, it is 50% more heat efficient than a line heater. The device can be divided into two major functional components, the heater and the power control assemblies.
The heater is 7/8 inches in diameter and consists of an electric resistance strip spiral wound. The power control assembly senses fuel temperature and responds by closing an electrical circuit to the heater. The sensing element is a bimetal switch. The internal bimetal switch turns on at 20 degrees F and shuts off at 46 degrees F. Power consumption is 110 watts @ 14 volts D.C. The heat will only be on until the under hood temperature gets hot enough to warm the fuel.
The heater can be sen/iced. However, it is retained in the filter base by the vent valve and an “ 0” ring. To remove it;
1. Remove the vent valve.
2. Disconnect the electrical connector.
3. Grasp the heater and remove it.
It can be checked by using an ammeter connected in series. Checking must take place below 20 degrees ambient temperature. Proper operation will draw approximately 8.6 amps.
