A fuel injection valve co-injects a liquid and a gaseous fuel into the combustion chamber of an internal combustion engine. A solid needle regulates the injection of liquid and gaseous fuels from a cavity in the fuel injection valve into the combustion chamber when the needle is lifted to its open position. In preferred embodiments, liquid fuel is metered and pressurized in an intensifier's cylinder provided within the valve body and the liquid fuel is delivered through a restricted flow passage into the cavity where it mixes with the gaseous fuel. The restricted flow passage can be formed by a small passage formed in the valve body or an annular passage between the needle and the valve body.