Early Fuel Evaporation System: Operation

When ignition switch is in the "ON" position, voltage is applied to a thermo switch located in intake manifold. If engine coolant temperature is below a calibrated value, the thermo switch completes the circuit to the heater, and allows current to flow.

The heater, incorporating a positive temperature coefficient semiconductor element, increases in temperature and then self- regulates at a calibrated temperature. This is in effect except at high engine speeds when air/fuel flow will reduce the temperature below regulated value. When coolant temperature reaches calibrated value, thermo switch turns off and current to heater is cut off.