In a multi-port fuel injection system for a lean burn engine, the attaching of fuel particles from the fuel spray onto a wall surface, which is a problem in atomizing injected fuel, is reduced, and the quality and shape of the mixed gas in the cylinders of the engine is improved. The engine has a fuel injector 1; an intake valve 6 for opening and closing an intake port; and an intake air flow control device 10. The injected fuel is shaped to provide a low penetration fuel spray when the engine is operated in a low load state and at a low rotation speed, and the injected fuel is shaped to provide a high penetration fuel spray when the engine is operated in a high load state and at a high rotation speed. The fuel is injected in synchronism with the intake stroke of the engine, and it is transported by the air flow flowing through the intake air flow control device 10 to suppress the attaching of fuel particles from the fuel spray onto a wall surface of the intake manifold.