There is provided a fuel injector system for vaporizing liquid fuel and metering the vapor to an internal combustion engine of an automobile. The system has at least one fuel injector with at least one capillary flow passage with a heat source arranged along the flow passage capable of heating liquid fuel in the flow passage to a level sufficient to vaporize it, a solenoid operated metering valve located at the capillary outlet for metering vaporized fuel to the internal combustion engine, and a system for operating the metering valve while delivering the vaporized fuel at an opening and closing frequency of at least 15 Hz or more preferably at least 60 Hz independent of engine rpm. The system is expected to be useful for starting a cold engine with reduced emissions.