Basic 2-Tube Canister

Gasoline vapors from fuel tank flow into canister and are adsorbed by carbon. Canister is purged when engine is running above idle speeds.

A timed vacuum source is applied to canister to draw fresh air through bottom of canister. Fresh air mixes with fuel vapors and are drawn into intake manifold to be burned in engine.

Some models are equipped with a second canister purge hose. This hose is connected to a Canister Control Valve (CCV). CCV is then connected to carburetor bowl vent line.

This allows carburetor bowl to be vented to canister, through CCV, when engine is not running. These vapors are then drawn into intake manifold once engine is started.