Abstract: A fuel supply system is composed of a fuel rail, a fuel injection valve and a fuel filter. The fuel injection valve has an electromagnetic solenoid, a valve member, a valve guide member and a valve seat. A plurality of slanted fuel passages are formed in the surface of the valve guide to evacuate bubble from the fuel. The fuel rail is composed of a resinous upper case member and a resinous lower case member. The fuel injection valve is held between the upper and lower case members in the axial direction of the valve. An elastic sheet member is interposed between the upper case member and the fuel injection valve, and an elastic O-ring is disposed around the fuel injection valve to reduce stress applied to the fuel injection valve in installing the fuel rail to an engine.