Evaporative Emissions System: Operation
When engine is stopped, fuel vapors flow from float bowl through open solenoid valve down into canister. Vapors from gas expanding in fuel tank pass through vapor separator, 2-way valve and into canister.
The purge line check valve is closed to prevent vapors from rising in the line and entering intake manifold. When ignition is turned on, solenoid valve closes, blocking off float bowl-to-canister passage. The thermal vacuum valve vents control vacuum to air cleaner until engine reaches temperature above 95°F (35°C).
Above the switching point, vacuum is applied to purge control valve. Manifold vacuum pulls fresh air into canister, through the purge line and into intake manifold. This fresh air purges fuel vapors from canister.
Note direction of flow.