Evaporative Emissions System: Description

An Early Fuel Evaporation (EFE) system is used on all Light Duty and some Heavy Duty emissions models. System provides improved cold driveability while reducing exhaust emissions. System consists of an EFE valve, an actuator and a Thermal Vacuum Switch (TVS). The TVS is coolant temperature controlled on V8 engines and oil temperature controlled on 6-cylinder engine.

NOTE: Some 1975 models with 454' engine use an engine oil temperature TVS. All other V8 engines are coolant temperature controlled.