Mercury Mariner Outboards 2.2 / 2.5 / 3.0 Service Shop Manual, Page 30Get this manual
Idle Speed Adjustment Start the engineAfter engine has been warmed upposition throttle lever at the lowest speed position Adjust idle speed screw to obtain recommended idle speed (900-1000 RPM)
Float Level Adjustment
Adjust float hinge as shown
.090(2.0mm)
(From Top of Gasket)
Throttle Jet Needle Adjustment
This carburetor is equipped with throttle valve that utilizes tapered jet needle (Step 5, page 3-6) to vary the fuel flow as the carburetor is opened Normally theE" ring is in the second groove Locating theE" ring closer to the end of the jet needle will "lean" the mixtureFurther leaning requires change of the main jetThe first indication of an overly rich mixture will be decrease in RPM as the carburetor is opened beyond 2 throttlei.emaxRPM will occur at less than wideopen-th rottle Change jet needle adjustment as follows1Remove carburetor from engine, as outlined in "Carburetor Removal" (see "Table of Contents")2Remove and disassemble throttle valve assembly, following instructions in carburetor disassembly 3ChangeE" ring groove and reassemble throttle valve assembly and carburetor as instructed inCarburetor Reassembly," following 4Reinstall carburetor as outlined inCarburetor Installation(see "Table of Contents ")