2005 SO Johnson 4 Stroke 9.9-15HP Outboards Service Manual, Page 110Get this manual
FUEL SYSTEM CARBURETOR OPERATION
Auto-Enrichener System
Remote models are equipped with an auto-enrichener systemThe automatic enrichener device consists of the PTC heater, the thermo-wax, and the plungerneedleWhen the thermo-wax is cold, the plungerneedle moves upward, and fuel is drawn into the enrichener circuit from the float chamberEnrichener jet meters this fuel, which then flows into fuel pipe and mixes with the air coming from the upper part of the float chamberThe mixture, rich in fuel content, reaches upper part of the fuel pipe and mixes again with air coming through passage extending from main boreThe two successive mixings of fuel with air are such that proper fuelair mixture for starting is produced when the mixture is sprayed out through outlet port into the main boreWhen the engine is coldThe auto-enrichener passage is open when the thermo-wax is at atmospheric temperatureWhen the engine is started: As PTC heater temperature increases, the thermo-wax gradually expands and closes enrichener passage with the needle of the plungerB 1234567