Abstract: A fuel injector is provided which has a valve member, a valve member guide and a spring chamber. Discharge of fuel out of a fuel injector outlet is controlled by movement of the valve member within a bore of the valve member guide. The spring chamber contains a biasing member, which is a compression spring, and which biases the valve member into contact with a valve seat when in a closed configuration. The fuel supply passage is provided, which by-passes the spring chamber, to direct a flow of the fuel to an outlet chamber of the fuel injector, and the cleaning fluid supply passage is provided to supply a pressurized cleaning fluid to a second end of the bore to restrict leakage of the fuel from the outlet chamber towards the second end of the bore along a clearance extending between the valve member and the valve member guide.

Abstract: A fuel injector (1) is provided which comprises a valve member (11), a valve member guide (12) and a spring chamber (40). Discharge of fuel out of a fuel injector outlet (21) is controlled by movement of the valve member (11) within a bore (23) of the valve member guide (12). The spring chamber (40) contains a biasing member (50), for example a compression spring, which biases the valve member (11) into contact with a valve seat (20) when in a closed configuration. A fuel supply passage (80) is provided, which by-passes the spring chamber (40), to direct a flow of the fuel to an outlet chamber (22) of the fuel injector (1) and a cleaning fluid supply passage (90) is provided to supply a pressurised cleaning fluid to a second end (25) of the bore (23) to restrict leakage of the fuel from the outlet chamber (22) towards the second end (25) of the bore (23) along a clearance (29) extending between the valve member (11) and the valve member guide (12).