Evaporative Emissions System: Description

In 1970 California and 1971 nationwide a fuel evaporative emission control system was introduced to control amount of gasoline vapors entering atmosphere from vehicle's fuel system. During periods of gasoline expansion and vaporization, fuel vapors from fuel tank and carburetor float bowl are routed to a charcoal filled canister where they are absorbed by the charcoal. When engine is operating, stored fuel vapors are drawn from canister into intake manifold and burned in engine. System consists of; a fuel tank with multiple vapor vent outlets, a fuel cap with vacuum and pressure relief valves, an expansion tank (liquid/vapor separator), a charcoal canister, an air flow control orifice, a float ball check valve (4x4 models only) and connecting lines and fittings.