Abstract: An apparatus for preventing freeze-up of a pressure regulator valve in a liquified petroleum fuel system by heating the valve, a fuel expansion chamber and the fuel, after it has been expanded to a gaseous state, to counteract the refrigeration action produced by expansion of the gas at atmospheric pressure. A heat pipe transfers heat from an internal combustion engine to the fuel expansion chamber, regulator valve and fuel. The fuel is heated to a selected temperature in the range of 80.degree. F. to 140.degree. F. The heat pipe can provide structural support to the fuel expansion chamber to facilitate the installation of the fuel conversion system. The heat pipe can comprise a metal pipe or a corrugated metal hose which allows relative movement between the condenser and the evaporator ends of the pipe. Additionally, a heat pipe using a porous wick can be used so that the fuel expansion chamber can be located below the attachment point of the evaporator portion of the heat pipe to the engine.