Abstract: Vapors normally arising within a standing gasoline tank are captured in a charcoal filled cannister. When the engine is running, air is drawn through the cannister thereby purging gasoline adsorbed on the charcoal within the cannister and delivering the purged gasoline vapors to the carburetor ultimately for combustion within the engine. Interference by the presence of such accumulated gasoline vapors in the carburetor, particularly during warm restarts and idling, can be avoided by preventing the injection of these gasoline vapors into the carburetor at the inappropriate times.