Abstract: An open nozzle unit fuel injector having an injector body for receiving a plunger assembly therein is disclosed including a fuel supply source for providing a metered quantity of fuel to a metering chamber formed in a central bore of the injector body to be injected into the cylinder of the internal combustion engine and a trapped volume spill port for a volume of fuel trapped in the metering chamber when the plunger has moved from its fully retracted position to its fully advanced position and injection has terminated. In accordance with the present invention, an open nozzle unit fuel injector is achieved which exhibits a sharp ending of injection, which prevents secondary injection and which significantly reduces the unburned hydrocarbon emissions of the engine incorporating such open nozzle unit fuel injectors including a trapped volume spill port.