INTAKE PASSAGE CONSTRUCTION FOR INTERNAL COMBUSTION ENGINES

摘要

An intake passage construction for an internal combustion engine has a primary intake passage for supplying an air-fuel mixture when the engine operates under a full range of loads and a secondary intake passage for supplying an air-fuel mixture when the engine operates under relatively high loads. A secondary slow fuel passage has a pair of fuel supply ports opening into the secondary intake passage, and a fuel drain passageway extends from one of the fuel supply ports and has a fuel discharge port opening into the primary intake passage. Ambient air can be introduced into the fuel drain passageway in response to a vacuum developed in the primary intake passage so that fuel can be drained from the secondary slow fuel passage to prevent vapor lock therein. The fuel discharge port of the fuel drain passageway may open into an induction pipe.