Abstract: A dual fuel system for a diesel engine includes a liquid (diesel) fuel injection system controlled by an engine electronic control unit (ECU) and a source of gaseous fuel such as natural gas. A metering valve and a mixer controls introduction of gaseous fuel from the natural gas fuel source into combustion air for the engine. An electronic governor controls the metering valve and a link controller coordinates operation of the ECU and the governor. Preferably, a regulator regulates the natural gas pressure supplied to the metering valve. A shut-off valve controls communication of natural gas between the source and the regulator. The link controller also controls the shut-off valve as a function of sensed conditions.