This Service Repair Manual covers the Mercury Mariner 30/40 (4-Stroke) outboard engine, manufactured from 1999 onwards, with serial numbers starting from 0G760300. These 4-stroke engines, offering 30-40 horsepower, are designed with a carburetor fuel delivery system and are available with either Non-Bigfoot or Bigfoot Gear Housings. The engineering quality and reliability of these Mercury Mariner outboards ensure dependable performance for various marine applications, making them a trusted choice for boaters. This comprehensive manual provides detailed instructions and technical information essential for maintaining and repairing your Mercury Mariner 30/40 (4-Stroke) engine. It includes extensive coverage of routine maintenance, general information, electrical systems, ignition, charging and starting, fuel systems, powerhead components, lubrication, mid-section, gear housing, and control linkage. With high-quality, color diagrams and printable pages, this manual is an invaluable resource for do-it-yourself owners and professional technicians alike, ensuring your engine operates at peak performance and longevity.