Evaporative Emissions System: Description and Operation

Evaporative Emissions Canister:

The carbon canister filled with activated charcoal granules is used as a vapor trap because of its great surface area, holding up to one-third its own weight in fuel vapors. The carbon canister is connected to the fuel tank by a vapor hose with an in-line metering type vapor valve and separator. Another vacuum/vapor hose connects the canister to the intake manifold. This second hose may contain an in-line purge control valve or solenoid. The carbon canister receives and stores fuel vapors, when the engine is OFF or when the vapors are not being routed directly to the induction system, when the engine is running. During purge conditions, as manifold vacuum is applied to the canister, fresh air is drawn through a vent on the bottom side of the canister. Fresh air allows stored fuel vapors to pass through the fuel vapor return line to the induction system.