Abstract: A fuel injection system for internal combustion engines in which fuel is metered out on the basis of the relative rotation of an air flow rate metering flap in the induction tube to a location upstream of the throttle valve. In order to prevent fuel condensation on the throttle valve during engine idling, the idling fuel quantity is delivered to a separate point in the induction tube lying downstream of the throttle valve.

Abstract: A fuel preparation system for an internal combustion engine employs an induction tube air flap which is shaped so as to be subject to aerodynamic lift forces when the air flow has caused a substantial displacement of the flap. In addition, the wall of the induction tube is made inwardly movable so that the net cross section available to the air flow may be reduced and a proportionately greater deflection rate obtained. The fuel quantity, which is related to the angular deflection is thus increased, causing a richer mixture. The air flap has internal channels which carry fuel from the pivotal shaft to the induction tube for injection into the air stream.