Mercury Owners Manual - 90-824720950. The Mercury Owners Manual - 90-824720950 is the official factory-issued guide specifically designed for owners of select Mercury outboard engines. This comprehensive manual delivers everything you need to operate, maintain, and troubleshoot your engine with confidence. Whether you're a new boat owner or an experienced marine technician, having the correct manual at your fingertips is essential for keeping your engine performing at its best.. Key Features. Ge