A fuel control system causes a fuel injector to interrupt fuel injection during a continuous decrease in engine speed to a lower limit of a hysteresis range for fuel supply/fuel interruption and to resume the interruption of fuel supply after a continuous increase in engine speed beyond an upper limit of the hysteresis range and further causes a compulsory interruption of fuel supply when a transition of the engine from non-deceleration to deceleration while the engine operates at speeds between the lower and upper limits of the hysteresis range.