1990 Johnson Evinrude "ES" 9.9 thru 30 Service Manual, P/N 507871, Page 46Get this manual
Idle Speed 1The 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 trailer Before proceeding with this procedure, be sure the lowspeed needle is properly adjustedRefer to Carburetor Adjustment, Section 21sl 2On tiller models, turn the idle speed knob fully counterclockwise to the full SLOW position3Start and allow the engine to reach normal operating temperature4When speed is reduced, engine must idle at 675 25 RPM in FORWARD gear_