A dual fuel system for an internal combustion engine includes a gaseous fuel subsystem and a liquid fuel subsystem. A plurality of fuel injectors each define a gaseous fuel passage fluidly connected to a gaseous fuel manifold of the gaseous fuel subsystem, a liquid fuel passage fluidly connected to a liquid fuel manifold of the liquid fuel subsystem, and a liquid fuel leak path from the liquid fuel passage to the gaseous fuel passage. A liquid fuel purging mechanism includes a drain conduit and at least one valve positioned fluidly between the drain conduit and the gaseous fuel manifold, and being adjustable to fluidly connect the drain conduit to the gaseous fuel manifold, to drain leaked liquid fuel to a low pressure outlet.