This manual covers the Yamaha 80-100 HP Outboard, Fourth Generation (F80/F100 models) produced between 2004 and 2006. These 4-stroke outboard engines are known for their reliable performance and fuel-efficient fuel injection systems, delivering between 80 and 100 horsepower. Engineered for demanding marine applications, these units offer robust construction and advanced TCI ignition for consistent power delivery. This Factory Service Manual provides comprehensive guidance for maintaining and repairing your Yamaha outboard. It details procedures for engine assembly and disassembly, troubleshooting common issues, and servicing electrical, fuel, cooling, and lubrication systems. Coverage extends to the lower unit, steering, and trim and tilt functions, offering essential information for owners and technicians to ensure optimal performance and longevity of the engine.