Fuel Evaporation System: Operation

When ignition switch is in "OFF" position, fuel tank and carburetor float bowl vapors are vented into charcoal canister. When engine is running above idle and warmed to normal operating temperature, thermo valve will open and allow vacuum to open purge control valve.

Canister vapors are then drawn into intake manifold through purge control valve for burning. Purge control valve is kept closed during idle and engine warm-up to reduce HC and CO emissions. On Mirage Turbo, purge control valve opens when the pressure difference between the turbocharged and throttle-port pressures exceeds a preset value.