Abstract: A gaseous fuel direct injection fuel system for a spark ignited internal combustion engine having an inlet port for admitting combustion air into a combustion chamber of the engine, the direction injection system including at least one fuel injector for directly injecting gaseous fuel into the combustion chamber, and means for supplying gaseous fuel to the fuel injector, a quantity of gaseous fuel being injected into the combustion chamber by the fuel injector, wherein at least at some operating condition thereof, the injection of the gaseous fuel is initiated after the closing of the inlet port, and wherein the injection of the gaseous fuel is completed before the compression stroke of the engine is substantially completed.