This manual covers the Yamaha 90A Outboard, an outboard engine designed for a wide range of marine applications. Engineered for reliability and performance, this model represents Yamaha's commitment to quality marine propulsion. Its robust construction and advanced design ensure dependable operation across various conditions, making it a trusted choice for boaters seeking efficiency and durability on the water. This Factory Service Repair Manual provides comprehensive guidance for the maintenance, diagnosis, and repair of your Yamaha 90A Outboard. It details scheduled maintenance, fault diagnosis, and step-by-step repair procedures for all major systems, including fuel, power, lower unit, bracket, and electrical systems, complete with detailed wiring diagrams. The manual includes an advanced troubleshooting guide and common fixes, enabling owners and technicians to effectively maintain the engine, reduce labor costs, and ensure optimal performance.