A fuel evaporation control, or vapor recovery system including: a charcoal canister housing therein activated charcoal adapted to adsorb gasoline vapor from a fuel tank; a purge port leading to a canister and opening into an intake passage in such a position that a throttle valve for the carburetor may assume an upstream position and a downstream position relative to the purge port, depending on its open positions; and a valve for controlling communication between the charcoal canister and a portion of the intake manifold, which is downstream from the throttle valve, in response to the operational condition of the engine. This fuel evaporation control system allows the vapor from the fuel tank to pass into the engine during engine deceleration or when the engine is loaded over a given load level. This system, however, interrupts the supply of gasoline vapor to the engine, during engine idling or when the engine is lightly loaded. Because of the supply of gasoline vapor during engine deceleration, the charcoal canister may provide capacity enough to retain the gasoline vapor when the engine is loaded over a given load level so that the size of the canister need not be increased and the cleaning time of gasoline vapor with air through the canister may be shortened.