Early Fuel Evaporation (EFE)

The ECM controls EFE system by either of the following methods: Vacuum operated valve and actuator, or ceramic heater grid located underneath carburetor primary bore. The vacuum operated valve and actuator is opened by a control solenoid mounted on valve cover.

This solenoid controls vacuum to EFE valve from an electrical signal supplied by ECM.

The ceramic heater grid system is part of carburetor insulator. When ignition is turned on and engine coolant temperature is low, voltage is applied to EFE relay through ECM, energizing EFE heater. When coolant temperature increases, ECM de-energizes EFE relay, which shuts off voltage to EFE heater.