Abstract: In a fuel supply control apparatus for an internal combustion engine having an A/F ratio feed-back control with a learning function, a difference between an A/F ratio detected by an oxygen sensor and the stoichiometric value is obtained and divided into an A/F ratio correction coefficient and an A/F ratio deviation coefficient in accordance with a predetermined gains ratio. The former coefficient is stored in an area of a correction map corresponding to an operational condition of the engine at that time and the latter coefficient is accumulated in an additional storage. Upon determination of an amount of fuel to be supplied, a former coefficient is read out from the map in response to the operational condition and added to the latter coefficient read out from the additional storage to form a correction value, which is used for correcting a preliminary fuel supply amount obtained in accordance with the operational condition to determine a final fuel supply amount.

Abstract: An intake system for an internal combustion engine has a fuel injector disposed in an induction passage upstream of a pivotally mounted throttle plate having an idle position in which the throttle plate has upstream and downstream edge portions slightly spaced from the inner peripheral surface of the induction passage to define therewith narrow gaps for the passage of air and injected fuel particles. A bypass air passage is formed in the peripheral wall of the induction passage and has a downstream end open thereto to produce a jet of air directed toward the central zone of the downstream face of the throttle plate when in the idle position. The air jet is operative to compensate for the difference in pressure between a central space immediately downstream of the throttle plate and peripheral zones adjacent to the narrow gaps whereby whirling-up of air and fuel particles just downstream of the throttle plate and resultant formation of drops of liquid fuel can be prevented.