The Evaporative Emission
Control System prevents fuel vapor stored in fuel tank from vaporizing
into the atmosphere. When the fuel evaporates in the fuel tank, the vapor
passes through vent hoses or tubes to a canister filled with charcoal.
The canister temporarily
holds the vapor in the charcoal. The ECM will control the system in order
to draw the gathered vapor into the combustion chambers during certain
operating conditions. Engine manifold vacuum is used to draw the vapor
into intake manifold.