Abstract: A system includes an engine, one or more gaseous fuel injectors configured to inject gaseous fuel for combustion by the engine, and an electronic control system configured to perform an engine shutdown, during the engine shutdown measure a first pressure of gaseous fuel supplied to at least a first injector of the one or more gaseous fuel injectors, command a first operation of the first injector comprising a plurality of shorter injection pulses, after the plurality of shorter injection pulses measure a second pressure of gaseous fuel supplied to the first injector, command a second operation of the first injector comprising one or more longer injection pulses, each of the one or more longer injection pulses having a duration greater that any of the plurality of shorter injection pulses, and after the one or more longer injection pulses measure a third pressure of gaseous fuel supplied to the first injector, diagnose the first injector in response to the first pressure, the second pressure, and the third pre