PURPOSE: To enhance the stability of engine running, in a fuel shut-off device in an automibile internal combustion engine, by providing such an arrangement that the cycle number of fuel injection signals is decreased to one half of the number of engine cylinders upon decelerating running so that fuel supply for one-half of the number of cylinders are restarted to restrain impact upon restart of fuel supply to a minimum value.

CONSTITUTION: In a fuel shut-off device for automobile engines, which carries out single fuel injection under electronic control, there are provided one fuel injection valve 6 disposed in an intake-air passage upstream of an intake-air manifold, an air-flowmeter 13, a crank angle sensor 14, a throttle valve switch 17 and a control unit 20. Further, in this device, there are provided a fuel injection control means for controlling the fuel injection valve 6 so that fuel injection with an amount for one engine cylinder is carried out every intake cycle of each cylinder, a releasing rotational speed setting means 29 for setting a rotational speed N2 at which fuel shut-off against a part of engine cylinders is released, between the rotational speed N1 and the shut-off releasing rotational speed N3, a rotational speed range discriminating means 26 for discriminating such a condition that the rotational speed of the engine is in a speed range from N3 to N2 and is upon deceleration, and a partial cylinder release setting means 31 for making the injection cycle number of the injection valve 6 one-half the number of engine cylinders.