Fuel injector

A fuel injector comprising a valve needle (14) which is slidable within a bore (12) and engageable with a valve needle seating to control fuel delivery through an outlet opening and a first supply passage (18) for delivering fuel under high pressure to the bore from a pump chamber (20). The valve needle (14) has a surface associated therewith which is exposed to fuel pressure within a control chamber (32). A control valve arrangement (36) is provided to control fuel pressure within the control chamber so as to control movement of the valve needle (14) relative to the valve needle seating. A spill/fill passage (28) is provided through which fuel at relatively low pressure is delivered to the pump chamber (20) under the control of a spill valve arrangement (60). The spill/fill passage is provided with a venturi pump (48) in communication with a backleak passage (46) through which fuel flows to a low pressure fuel reservoir.