A fuel injector is provided. The fuel injector includes a sleeve having a first end proximate an outlet; a piston slidingly received in the sleeve, the piston having a first end proximate the outlet; a pumping chamber at least partially defined by the sleeve between the first end of the piston and the outlet; and a normally-open inlet valve through which fuel passes to enter the pumping chamber.

A fuel injection device comprising electricity-generating means generating electricity by rotation of an engine and outputting a predetermined signal, and a solenoid valve injecting fuel; the valve being opened as a result of a drive current applied to a coil, and the fuel being injected into an intake passage of the engine at a predetermined timing during the rotation of the engine; to ensure that the flow rate required during high-speed operation ca be adequately provided in a fuel injection device for injecting/supplying fuel to an engine. The electricity-generating means is an alternating current generation means attached to the engine in a crank angle position at which an output is generated in synchronization with the intake timing of the engine; the signal is an injection command signal applied to the solenoid valve as an alternating-current drive current; and the applied voltage increases with increased engine speed.