This document pertains to the Mercury Mariner 90 HP Outboard, a robust and reliable engine designed for a variety of marine applications. While specific production years are not detailed, this manual covers multiple styles and serial number ranges, particularly concerning Power Trim systems. The engineering quality of the Mercury Mariner series is recognized for its performance and durability, making it a trusted choice for boaters. This manual provides comprehensive information to ensure the optimal functioning and longevity of your outboard. The purpose of this Factory Service Repair Manual is to provide detailed guidance for the maintenance, repair, and troubleshooting of the Mercury Mariner 90 HP Outboard. It encompasses a wide range of topics, including engine components, fuel and electrical systems, trim and tilt mechanisms, and controls. With hundreds of pages of high-resolution content, including essential illustrations, diagrams, and photos, this manual offers step-by-step instructions and expert techniques. It is an indispensable resource for owners, mechanics, and technicians seeking to perform accurate diagnostics and repairs, ensuring the continued performance and safety of the vessel.