This service repair manual covers Mercury Mariner 40/50/60 EFI (4-Stroke) outboard motors, specifically those with serial numbers starting from 1C050252 and above. These 4-stroke EFI engines, available in 40, 50, and 60 horsepower configurations, are engineered for reliable performance in various marine applications. This manual provides comprehensive information to ensure the optimal operation and longevity of your Mercury Mariner outboard motor. The purpose of this English-language service repair manual is to guide both do-it-yourself owners and experienced mechanics through all aspects of maintenance and repair. It includes detailed coverage of important information, electrical systems, electronic fuel injection, powerhead, mid-section, lower unit, attachments/control linkage, and jet drive outboards. With easy-to-read text, high-quality diagrams, and step-by-step instructions, this manual is an essential resource for maintaining and troubleshooting your outboard motor, mirroring the information used by local dealers.