Fuel Emissions System: Operation

When engine is off, fuel vapors are collected in vapor storage tank. Some vapors are condensed in storage tank and flow back into fuel tank. Excess vapors continue to charcoal canister, where they are absorbed. When engine is started, vacuum in intake manifold draws vapor from canister and storage tank. These vapors are then drawn into the engine and burned. Vapor storage tank also allows for fuel expansion of a completely filled fuel tank.