a plunger reciprocatingly disposed within a bore;

a nozzle member having a tip end with at least one orifice;

a valve needle having a base end and tip end, being disposed within the nozzle member, and movable against a spring bias from a flow blocking position at which substantially no fuel flows through the at least one orifice, to a flow passing position at which fuel flows through the at least one orifice;

a check valve in fluid communication with the bore and the base end of the valve needle, the check valve movable between a first position at which the base end of the valve needle is fluidly communicated with the bore, and a second position at which the base end of the valve needle is fluidly communicated with a drain;

a spill valve associated with the bore and movable between a first position at which fuel flows from the bore to the drain, and a second position at which the fuel from the bore is blocked from the drain; and

a controller in communication with the check valve and the spill valve, the controller being configured to:

move the spill valve toward its second position during a downward displacing movement of the plunger to build pressure within the bore;

move the check valve toward its second position during the downward displacing movement of the plunger;

detect an unsuccessful movement of the check valve to the second position; and

prematurely halt a current injection event in response to the detection.