Abstract: An engine powered by fuel having a boiling temperature less than ambient wherein the fuel is stored as a liquid and delivered in the liquid state to a fuel injection system. The fuel is sprayed into the intake port region of a cylinder head as liquid droplets which then vaporize. The fuel supplied to the injection system is maintained in the liquid state by a cooling system which maintains the liquid fuel below the boiling temperature. One cooling system includes a tube coiled around the injection system through which a refrigerant is circulated and cooled by a refrigeration system. A bleedoff conduit withdraws any excess fuel from the injection region and returns it to the fuel storage tank.