PURPOSE: To collect fuel droplets in a fuel reservoir during a low-speed operation of an engine and to effectively adomizing the collected fuel for enhancing combustibility by arranging an auxiliary suction passage bypassing each suction passage of a multi-cylinder internal-combustion engine and providing the reservoir at the tip end of the auxiliary passage.

CONSTITUTION: A suction passage 15 is communicated with an engine 7, and an auxiliary suction passage 22 is provided which bypasses the passage 15 and communicates the upstream side of a throttle valve 16 with a suction port 4. In the passage 22 are arranged an auxiliary throttle valve 23 and a common communication passage 21 communicating between cylinders. At the tip end portion opening into the port 4 are provided a fuel reservoir 18 and a perforated plate 20 thereon. In a low-speed operation of the engine 7, the valve 16 is closed and the valve 23 opened, to introduce air from the passage 22. As a result, the fuel droplets injected from a fuel injection valve 14 and collecting in the reservoir 18 are blown off and atomized effectively.