The vaporizing liquid fuel system converts virtually all of the liquid passing through it to a vapor state for chemical or physical processes in the vapor state. One chemical process is combustion in an engine or fuel burning apparatus such as a heating device. The evaporator is comprised of a vapor chamber enclosed by a tube having liquid inlet and vapor outlet ports. The vapor chamber is virtually filled with a thermally conductive vaporizing surface. In the preferred embodiment the thermally conductive vaporizing surface is bonded to the inner surface of the tube. Heat is applied to the other surface and is conducted into the thermally conductive vaporizing surface where vaporization occurs. Heat may be supplied by a resistive film heater bonded to the outer surface of the tube, by heat conducted from a fuel burning system, by heat carried by fluid circulated from a fuel burning system.