1992 Johnson Evinrude "EN" 9.9 thru 30 Service Manual, P/N 508142, Page 86Get this manual
Carburetor Mixture Adjustment, 9.915 1Start the engine and run it in FORWARD at one-half throttleAllow the engine to reach normal operating temperature2Turn the idle adjusting knob to full SLOW position3Run the engine at slow speed (700-S00 RPM) and adjust the low-speed needle until the highest consistent RPM is attainedAllow 15 seconds after each adjustment for the engine to respond4After the final adjustment is completed, turn the low-speed needle counterclockwise one-eighth turn to prevent lean condition, particularly in NEUTRAl
Remove the mixture knobReposition it with its pointer downBe careful not to disturb position of low-speed needle
6Reduce engine speed and turn the idle speed adjustment to allow the engine to run at minimum of 650 RPM in FORWARD7Run the engine in gear near full throttle for one minuteQuickly reduce speed to SLOW (700-S00 RPM) and shift into NEUTRAlThe engine should continue to run smoothlySIf the engine stalls or pops, the mixture is too leanTurn the needle counterclockwise 116 turnAllow 15 seconds after each adjustment for the engine to respondRepeat Step to verify that the mixture adjustment is correct9If the engine does not respond to adjustments, check it for other problemsMake sure gasoline is of good quality and mixed with the proper amount of oil