1990 Johnson Evinrude "ES" 9.9 thru 30 Service Manual, P/N 507871, Page 92Get this manual
Carburetor Mixture Adjustment, 20-30 The slow speed mixture in this carburetor is controlled by factory adjusted needleThis procedure should only be used if the factory seal is gone or if the needle adjustment has been disturbedf"18l 1Make reference mark on the adapter sleeve before you the needle adjustment2The boat must be in the water, under normal operating conditions with the correct propeller installedThe boat's movement must be unrestrainedThe boat must not be tied to dock or trailer3Start the engine and allow it to reach normal operating temperatureRun the engine in gear at slow speed (700-800 RPM) for three minutes If the adjustment is too lean, the engine will sneeze and back-fire, go to Step Ifthe adjustment is too rich, the engine will be rough and unsteady, go to Step 5[!!} 4If the adjustment is too lean, notice your reference mark and turn the needle 1112 revolution counterclockwiseWaiting 15 seconds after each adjustment, repeatthis procedure until you reach the highest consistent RPM[!!} 5If the adjustment is too rich, notice your reference mark and turn the needle V12 revolution clockwiseWaiting 15 seconds after each adjustment, 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 57Use RTV Sealer, OMC PIN 263753, to seal the end of the adapter sleeveIf the engine does not respond properly to these adjustments, check the following: Engine temperature Linkage adjustments External recirculation system Sufficient exhaust back pressure