This comprehensive Service Repair Manual covers the Mercury Mariner 30/40 4-Stroke outboard motor, beginning with the 1999 model year and starting serial number 0G760300. Engineered for reliability and performance, these 4-stroke outboard motors are designed to provide dependable power for a variety of marine applications. This manual is the most complete resource for understanding and maintaining these robust engines. The purpose of this manual is to provide detailed guidance for the maintenance, repair, and troubleshooting of your Mercury Mariner 30/40 4-Stroke outboard motor. It includes essential information such as specifications, general operating procedures, electrical system details, fuel system components, powerhead and mid-section servicing, gear housing repair for both Non-Bigfoot and Bigfoot types, and more. With clear instructions and high-quality diagrams, this manual serves as an indispensable tool for owners and technicians alike to ensure the longevity and optimal performance of the outboard motor.