Abstract: This invention relates to the precision control of the rate of fluid flow in fluid conducting lines, and is particularly applicable to the control of gaseous fuel to an internal combustion engine. The fluid is caused to flow through a plurality of parallel lines each of which contains a solenoid valve operated by digital signals from an electronic digital processor. A plurality of sensors associated with the internal combustion engine monitor operating parameters, and provide signals to the electronic digital processor representative of the parameters. The relative flow rates of the lines are proportional to successive powers of two, and are determined by orifices in the lines which provide the above-noted relation flow rates in said lines at pressure differentials thereacross which are at or above that necessary to provide critical or choked flow in such orifices.