In a magnetic valve controlled fuel injector for a storage fuel injection system of a multi-cylinder internal combustion engine wherein the injector includes an upper housing part with a control piston, a lower housing part with a valve piston, a nozzle body with a spring loaded needle valve, and a fuel supply passage extending through the lower housing part to the valve piston and through the valve and control pistons to a control chamber from which fuel can be released under the control of a magnetic valve disposed on top of the upper housing part. The fuel supply passage further extends from the valve piston to a pressure chamber around the nozzle needle which when unseated by opening the magnetic control valve permits ejection of fuel from the pressure chamber. The valve and control piston which are disposed in the lower and respectively, upper housing parts are disposed in engagement with each other in the area of the jointure of the upper and the lower housing parts.