CRESSIDA & Supra
The fuel evaporation system is controlled by a bimetal vacuum switching valve (BVSV) and check valves. When the engine is stopped, coolant temperatures are low. When engine is idling, fuel vapors from tank are routed to charcoal canister and stored.
When engine is accelerating or running at road speed, BVSV opens, allowing fuel vapors from canister to be drawn into intake manifold. The system also uses 3 check valves in the charcoal canister. These control fuel tank pressure and vent excess vacuum from tank.