Abstract: Methods and means are disclosed for controlling the flow of gasoline through the idle jet of the carburetor of an automotive internal combustion engine. To improve mileage, flow through the idle jet is discontinued when the vehicle is traveling above a minimum speed provided that the vacuum in the intake manifold does not fall too low. Additional fuel economy may be obtained by stopping the flow of gasoline through the idle jet at any time the throttle is advanced and fuel flows through the main jets of the carburetor.In the simplest mechanical embodiment of the invention, the flow of fuel through the idle jet feed line is controlled by an atmospheric vent provided in the idle jet feed line. When the vent is open to atmosphere, the vacuum from the intake manifold is broken and no fuel will be drawn from the carburetor float bowl by the idle jet to the engine.