This workshop service repair manual covers the Mercury Mariner 250 HP EFI Outboard, designed for robust performance and reliability in marine applications. Engineered with Electronic Fuel Injection and a powerful V6 configuration, this outboard delivers exceptional power and efficiency. Its advanced CDI ignition system ensures consistent operation, while the durable lower unit is built to withstand demanding conditions. This manual provides comprehensive information for all models and engines, reflecting the quality and innovation synonymous with Mercury Mariner marine propulsion. The purpose of this manual is to provide detailed guidance for the maintenance, repair, and technical understanding of the Mercury Mariner 250 HP EFI Outboard. It includes essential information on routine service intervals, lubrication, filter and spark plug replacement, and cooling system maintenance, such as water pump impeller service. Furthermore, the manual covers technical specifications, troubleshooting procedures, and electrical system details, equipping owners, mechanics, and technicians with the knowledge necessary to ensure optimal performance and longevity of their outboard engine.