Abstract: An integrated fuel injector and ignitor assembly is provided which includes an injector body, a fuel control valve and an ignition device. The components are packaged to create a compact assembly for positioning within an injector mounting bore and particularly in a mounting bore of an existing diesel engine. The assembly may include a fuel reservoir for accumulating fuel for injection so as to stabilize the injection pressure. Also, the ignition device may include an ignition coil mounted on the injector body and a replaceable ignitor electrode cartridge mounted on an opposite end of the injector body to permit simple, cost effective replacement of the electrodes/spark plug.