Mercury Mariner 8/9.9HP 4-Stroke Factory Service Manual, Page 102Get this manual
Carburetor Adjustments Pilot Mixture Screw
(NOT APPLICABLE TO BODENSEE MODELS)
Float Level Adjustment
1With carburetor turned upside down and depth micrometer seated on inner ledge, check float level from top of float to float bowl flange as shown
NOTE: The pilot mixture screw is set at the factory and normally should require no adjustment1If adjustment to the pilot screw is required, adjust screw as follows: aTurn pilot mixture screw in (clockwise) until LIGHTLY seated then back out to an initial setting of turnsbAdjust pilot mixture screw for best performanceWith engine running at slowidle speed in "Forward" gear, turn mixture screw "In" (clockwise) until engine starts to lose R.P.M then back out 14 turn
NOTE: When setting pilot mixture screw, DO NOT adjust leaner than necessary to attain reasonably smooth idlingAlso allow time for engine to stabilize between adjustments