Evaporative Emissions System: Description

BMW Evaporative Control System consists of a purge system, leading from fuel tank to hose of crankcase ventilation system. Located between fuel tank and crankcase ventilation system is a vapor storage tank and an activated carbon canister. Fuel evaporation emissions are prevented from entering atmosphere by means of a sealed filler cap on fuel tank. Fuel tank has no direct vent to atmosphere. An excess fuel return valve is also used, located in fuel supply line near carburetor. A fuel return line connects this valve to fuel tank.