1998+ Mercury Mariner 25HP Bigfoot Service Manual, Page 176Get this manual

EMISSIONS
Stoichiometric (14.7:1) AirFuel Ratio

Outboard Hydrocarbon Emissions Reductions
8 13PER YEAR OVER MODEL YEARS

• ATV
• Jet Ski
• Outboard Motors
• Personal Watercraft
• Snowmobiles
• Stern Drives