Fuel Evaporation System: Operation
Expanded fuel caused by high temperatures is collected in expansion chamber. When engine is stopped, fuel tank vapors flow through a vent line to charcoal canister, where they are stored.
When engine is running above idle speed, intake vacuum draws fresh air through charcoal canister and pulls stored vapors into the intake system through the air cleaner. When engine is at idle, fuel vapors flow from the charcoal canister to the intake manifold to be burned.
The charcoal filter valve, located between the charcoal canister and air intake duct, reduces hydrocarbon emissions by closing at idle to prevent vaporized fuel from entering air intake.
As speed increases, the charcoal filter valve opens and allows vapors, stored in the charcoal canister, to enter intake duct to be burned by the engine.