Feedback Carburetor System: Operation
Control unit adjusts fuel mixture by controlling the frequency solenoids. When frequency solenoid B is opened, manifold vacuum is applied to air control B. When air control B is opened, air is allowed to enter intake manifold. When frequency solenoid A is opened, air control valve A (if opened by carburetor port vacuum) will allow air to enter intake manifold. The air entering the intake manifold from air control A is proportional to amount of intake air volume.