Abstract: An air valve for a fuel injection system of a mixture-compressing externally ignited internal combustion engine which controlls the air flow in a bypass line associated with the air suction tube, the bypass line bypassing a throttle valve mounted within the suction tube. The air valve includes a membrane which defines a first and second chamber of the valve, the first chamber of which is in communication with atmosphere. The air valve also includes a movable valve component mounted to control the cross-sectional area of the bypass line. The movable valve component is connected to the member by a guide pin, and the movement of the movable valve component is responsive to an arrangement of a guide spring and pressure spring as well as the pressures in the two chambers.