Fuel Evaporation System: Operation
When the engine is not running, purge valve opens fuel tank vapor line to canister and switch vent solenoid opens float bowl vent to canister.
When the engine is running and warmed to normal operating temperature, bi-metallic vacuum switching valve (BVSV) closes and allows a carburetor vacuum signal to open purge control valve. With the purge valve open, manifold vacuum draws canister vapors into combustion chambers for burning.
The two-way check valve is used to balance vapor pressure between fuel tank and canister.