Evaporative Emissions System: Description and Operation

2S-E, 3S-FE, 3S-GE, 4A-GE, 4A-GEC, 4A-GEL, 4A-GELC, 5M-GE, 7M-GE, 7M-GTE & 22R-E ENGINES
The system for these models includes a bi-metal vacuum switching valve which responds to coolant temperature. When temperature is below 95° F, the BVSV is closed and vapors are stored in the charcoal canister. At temperatures above 129° F, with throttle valve opening positioned below purge port, No. 1 check valve is closed, trapping vapors in canister. When position of throttle valve opening is above purge port, vapors are led into the air intake chamber to be burned during combustion.