Charge forming device with controlled air bypass

摘要

A charge forming device includes a body with a fuel and air mixing passage, a bypass passage that communicates with the fuel and air mixing passage, a throttle valve and a choke valve. The throttle valve is movable between idle and wide open positions and operable to control at least in part the fluid flow through the fuel and air mixing passage. The choke valve is movable between an open position permitting a substantially free flow of air into the fuel and air mixing passage and a closed position at least substantially restricting air flow into the fuel and air mixing passage. A bypass valve is movable between an open position and a closed position to selectively permit fluid flow through the bypass passage. The bypass valve is movable toward its open position when the throttle valve is displaced at least a threshold amount away from its idle position.