This manual covers the Mercury Mariner SeaPro, a robust outboard engine designed for demanding marine applications. Featuring a powerful 3.0L displacement and advanced Electronic Fuel Injection (EFI), the Mariner SeaPro is engineered for reliability and performance. Its SeaPro variant designation indicates enhanced durability and suitability for commercial or heavy-duty use, ensuring consistent operation in challenging conditions. The water-cooled system and electric start provide essential functionality for a seamless boating experience. This Service Repair Workshop Manual provides comprehensive instructions for mechanics to maintain and repair the Mercury Mariner SeaPro 3.0L outboard engine. It details essential procedures for routine maintenance, lubrication, and troubleshooting, ensuring the engine operates at peak efficiency. Technical specifications, including details on the ignition, fuel, cooling, and trim and tilt systems, are included to facilitate accurate diagnostics and repairs. Adherence to the guidelines within this manual is crucial for preserving the longevity and performance of your Mercury Mariner SeaPro.