PURPOSE: To obtain improved fuel atomization and to improve engine performance by intermittently opening and closing, by a pulse motor, a valve body of an injection valve provided on revolving axis of an air valve which is equipped in place of Venturi as a negative pressure generator.

CONSTITUTION: At a portion upper stream than throttle valve 3 of inlet air channel 2, a disk type air valve 4 is provided and supported as bearing tube 14 provided in the center of valve 4 is revolvably inserted on shaft 11. Air valve 4 and bearing tube 14 have notch 15 which causes injection tip 13 provided on sahft 11 and being opened diagonally to the lower be kept opened and exposed toward mixture chamber 5. Connected to end portion of bearing tube 14 is motor 17 consisting of a revolving potentiometer and opening/closing mechanism 16 consisting of gear 18. Chamber 19 within shaft 11 is inserted with injection valve 6 having valve body 20 which has valve channel 21 to fuel supply channel 12. Valve body 20 is intermittently driven by pulse motor 7 contolled by controller 31 which generates driving current consisting of a group of pulses.