This Service Repair Workshop Manual covers the Mercury Marine Mariner Optimax Jetdrive engines produced between 2002 and 2004. These first-generation Optimax Jetdrive models are characterized by their 2-stroke direct injection technology, a 3.0L displacement, and a power output of 250 HP. Engineered for reliability and performance, these engines feature direct fuel injection, an oil injection system, CDI ignition, and a water-cooled system, all integrated with a jet drive transmission. This comprehensive manual provides essential information for the maintenance, repair, and troubleshooting of your Mercury Marine Mariner Optimax Jetdrive. It includes detailed sections on general information, specifications, jet installation, powerhead assembly, cooling systems, pump unit, fuel system components including direct fuel injection and oil injection, electrical systems covering ignition and charging/starting, and emissions. With the inclusion of diagrams and wiring schematics, this manual is an indispensable resource for owners and technicians to ensure optimal performance and longevity of the engine.