Small two-wheel vehicles have secured a solid position as a major means of transport in many countries in the world. Meanwhile, more stringent emissions standards, typically EURO-3, are expected to be introduced in various countries by 2006. This calls for the shift of fuel supply systems for small two-wheel vehicles from carburetors, the present mainstay, to more precision, highly controllable electronic fuel injection systems.
However, conventional fuel injection systems require various functional components including a fuel pump, regulator and injectors. Particularly, the need for location of the fuel pump within the fuel tank will present layout problems to small two-wheel vehicles that have a relatively limited tank capacity. Moreover, the fuel pump must continue to run at all times to hold fuel at a high pressure for supply to the injectors. Consequently, much consumption current is required. To overcome all these problems, a discharge pump type fuel injection system has been developed that can efficiently handle atmospheric pressure fuel as do carburetors, as well as provide precision control over fuel injection comparable to conventional fuel injection systems.