Early Fuel Evaporation ( EFE ): Description and Operation

Fig. 1 EFE system:

The EFE system, Fig. 1, is comprised of the EFE heater, electronic control module, coolant temperature sensor and the EFE relay assembly.
The EFE heater has a ceramic ring. This ring, located beneath the carburetor primary bore is part of the carburetor insulator gasket.
The EFE warms the incoming air/fuel mixture, improving vaporization which increases performance on cold drive-away. The coolant temperature sensor is activated with the engine operating. If engine coolant temperature is below a predetermined value, the electronic control module (ECM) will supply current from the battery to the EFE heater relay coils, heating the air/fuel mixture. The heater has a positive temperature coefficient (PTC) semiconductor element. The resistance of this element will increase as heater temperature reaches a predetermined value, which decreases battery current and heater temperature.
At high engine speeds, this action will not occur as the high volume of air/fuel flow will prevent heater temperature from rising to the prescribed level.
When overall coolant temperature reaches a predetermined value, the ECM will cut off the current to the EFE heater assembly.




Diagnosis & Testing
For EFE system diagnosis and testing procedures, refer to ``Computerized Engine Controls Section.''

Service
Check EFE heater assembly for cracks and/or damage. Replace EFE heater assembly, if necessary.