This manual covers the Mercury/Mariner Optimax Jet Drive, specifically the 250HP model. This powerful engine features Optimax Direct Injection 2-Stroke technology, a Direct Fuel Injection system, and Electronic Ignition, delivering exceptional performance for its class. Engineered for reliability and efficiency, the Optimax Jet Drive is designed to provide a robust and dependable boating experience, making it a premier choice for a variety of marine applications. The Complete Service Manual provides comprehensive repair and service information for do-it-yourselfers and experienced mechanics alike. It details maintenance procedures including lubrication, tuning, and oil injection, alongside service procedures for key components such as the power head, gearcase, tilt trim, and starters. Troubleshooting guidance, including electrical system diagnostics with detailed wiring diagrams, is also extensively covered. This manual is your essential resource for maintaining and repairing your Mercury/Mariner Optimax Jet Drive.