Operating a fuel system for an engine includes moving a plunger during a pumping cycle between an advanced position and a retracted position, and pulsing a solenoid actuator in an electrical circuit during at least one off cycle of the plunger where the plunger is neither advancing nor retracting with a plurality of current pulses of varied duration. An electrical property such as a freewheeling response in the electrical circuit induced by moving a valve in response to each respective current pulse is monitored, and a valve timing of the valve determined based on the monitored electrical property. The fuel system including a fuel injector may be electronically trimmed based on the determined valve timing. Related apparatus and control logic is also disclosed.

Operating a fuel system for an engine includes moving a plunger during a pumping cycle between an advanced position and a retracted position, and pulsing a solenoid actuator in an electrical circuit during at least one off cycle of the plunger where the plunger is neither advancing nor retracting with a plurality of current pulses of varied duration. An electrical property such as a freewheeling response in the electrical circuit induced by moving a valve in response to each respective current pulse is monitored, and a valve timing of the valve determined based on the monitored electrical property. The fuel system including a fuel injector may be electronically trimmed based on the determined valve timing. Related apparatus and control logic is also disclosed.