2001-2002 Yamaha 50HP F50Z/T50Z Ouboard 4-stroke engines service manual, Page 127Get this manual
Troubleshooting Symptom: The engine idle speed is not steady, but increases or decreases Check the carburetors Check the air intake system Check the ignition system
Check the operation of the carburetor throttle valves
Do the valves close simultaneously?
Check the ignition timingCheck the secondary air intake on the O-ring and manifold plate, and the gaskets of the vacuum check bolts