1997+ Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-826148R2, Page 156Get this manual
Possible Cause Improperly mixed fuelContaminants(water, dirt, etc in fuelFuel tank air vent closed or restrictedA pinched, cut or restricted fuel lineAlso loose fuel line connectionDirty or restricted fuel filterLow fuel pump pressureDefective anti-siphon valveNeedle and seat in carburetor that is either stuck open or closedImproper carburetor jet, restricted jet or idle mixture screw out of adjustmentImproper float levelCarburetor loose on intake manifold Corrective Action Check fuel in tank and replace if necessaryCheck air vent on tankVent must be open all-theway and free from any contaminantsInspect all fuel lines and replace as neededInspect and tighten all fuel line connectionsInspect and replace or clean all fuel filtersRefer to Section 3B "Fuel Pumps Refer to Section 3B "Fuel Pumps Refer to carburetor adjustments in this sectionRefer to carburetor adjustments in this sectionRefer to carburetor adjustments in this sectionCheck 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" sectionRefer to Section 3B, "Fuel Pump Tighten screws or replace gasketBlow with compressed airBlow with compressed airRefer to Section 4A for reed inspection