1986+ Mercury 6/8/9.9/10/15HP 2-stroke Factory Service Manual, Page 129Get this manual
FUEL DELIVERY SYSTEM
Possible Cause Improperly mixed fuelContaminants (water, dirt, etc in fuelCarburetor loose on intake manifoldReed block loose or gasket defective
Corrective Action Check fuel in tank and replace if necessaryCheck tightness of carburetor nutsUsing pressure oil can, apply 2-cycle oil around reed block housingcrankcase housing matching surfaces and carburetor baseIf engine RPM changes, tighten boltsnuts or replace gaskets as requiredRefer to bleed hose routing in Powerhead sectionDisassemble and inspect fuel pump componentsTighten screws or replace gasketBlow with compressed airBlow with compressed airRefer to Section for reed inspectionReplaceInstall correct plug or readjust gapReset timing to correct specificationsReplace diaphragm
Improperly routed or restricted bleed hosesDamaged fuel pump diaphragmCarburetor mixing chamber cover leaking airOff idle holes pluggedMain nozzle or idle nozzle air bleed holes pluggedDamaged reedsFuel pick-up outlet tube in fuel tank crackedWrong spark plug or improper spark plug gapImproper spark timingEnrichener diaphragm leakingProblem: Engine Floods Possible Cause Dirt or debris are preventing inlet needle from seatingWorn inlet needlePunctured floatIncorrect float settingProblem: Engine Runs Too Rich Possible Cause Fuel level too highCarburetor floodsIdle nozzle air holes pluggedRestricted air flowMain fuel jet loose