Early Fuel Evaporation ( EFE ): Description and Operation

Vacuum Operated EFE System:

The EFE system is provided as a source of rapid heat to the engine intake system during cold driving. Rapid heating is needed to provide quick fuel evaporation and more uniform fuel distribution and aid cold driveability. It also reduces the length of time the choke is required, so it reduces exhaust emissions.


The EFE system uses a valve and vacuum actuator to increase the exhaust gas flow through the intake manifold during cold engine operation. The valve is located in the exhaust and is vacuum operated. It is controlled by a Thermal Vacuum Switch (TVS). When vacuum is applied, the valve closes, causing the intake to heat up.

RESULTS OF INCORRECT EFE OPERATION

No EFE:
^ Engine may stumble and stall during warm-up.
^ Engine takes longer time to warm up.
^ Choke may heat up and be "OFF" before engine is warm.

EFE stays "ON":
^ Poor performance.
^ Lack of power when warm due to superheated gases.
^ Engine may overheat.