Early Fuel Evaporation System: Description

Early Fuel Evaporation (EFE) system is used on General Motors light and heavy duty 4.8L, 5.0L, 5.7L and 7.4L trucks. EFE system is used to provide heat to engine induction system during cold driveaway. EFE system is vacuum operated exhaust heat riser valve type. EFE system provides rapid heating, resulting in faster fuel evaporation and more uniform fuel distribution. This also helps reduce choke "ON" time by warming engine faster.

Fig 1: EFE System (6-Cylinder Engines)

Courtesy of GENERAL MOTORS CORP.

Fig 2: EFE System (V8 Engines)

Courtesy of GENERAL MOTORS CORP.