An apparatus for delivering two fuels to a direct injection internal combustion engine comprises a liquid-fuel supply rail, a gaseous-fuel supply rail, a drain system with a shared drain rail for collecting both liquid fuel and gaseous fuel, and a venting device for venting gaseous fuel collected by the drain rail. The method comprises separately delivering a liquid fuel at injection pressure to an injection valve through a liquid-fuel rail, and actuating the liquid-fuel injection valve to introduce liquid fuel directly into the combustion chamber. The method further comprises delivering a gaseous fuel at injection pressure to an injection valve through a gaseous-fuel rail and actuating the gaseous-fuel injection valve to introduce gaseous fuel directly into the combustion chamber. The method further comprises collecting in a drain rail liquid fuel and gaseous fuel from the liquid-fuel injection valve and the gaseous-fuel injection valve, directing liquid fuel to a storage vessel, and directing gaseous fuel to a vent pipe.