1993 Johnson Evinrude "ET" 9.9 thru 30 Service Manual, P/N 508282, Page 99Get this manual
Carburetor Mixture Adjustment, 2530 The slow speed mixture in this carburetor is controlled by factory adjusted needleThis procedure should be used only if the needle adjustment has been disturbed'16l 1Make reference mark on the adapter sleeve before you disturb the needle adjustment
r:;J 2Tiller modelsas you face the steering handle, turn idle speed adjustment knob counterclockwise to full SLOW speed position3Start the engine and run it in gear, at slow speed (700-800 RPM), for three minutesAllow it to reach normal operating temperature If the adjustment is too lean, the engine will sneeze and backfireGo to Step Ifthe adjustment is too rich, the engine will be rough and unsteadyGo to Step 5'16l 4If the adjustment is too lean, note your reference mark and turn the needle '112 revolution counterclockwiseWait 15 seconds after each adjustment and repeat this procedure until you reach the highest consistent RPM'16l 5If the adjustment is too rich, note your reference mark and turn the needle V,2 revolution clockwiseWait 15 seconds after each adjustment and repeat this procedure until you reach the highest consistent RPM6To test your adjustment, run engine near full throttle for three minutesReturn the engine to idle, in gearThe engine should maintain smooth idle RPM If your test results vary, repeat Steps thru 5If the engine does not respond properly to these adjustments, check the followingEngine temperature Linkage adjustments External recirculation system Sufficient exhaust back pressure