1986+ Mercury 6/8/9.9/10/15HP 2-stroke Factory Service Manual, Page 128Get this manual
FUEL DELIVERY SYSTEM
Fuel System Troubleshooting
General Information
Problems thought to be caused by the fuel system may be caused by one or more of the following six items listed below1Propeller 2Spark Plugs 3Ignition Timing 4Ignition Spark Voltage 5Cylinder Compression 6Reed Valves Typical symptoms and solutions in troubleshooting fuel system are shown below: Problem: Engine Turns Over but Will Not Start or Starts Hard When Cold Problem: Engine Idles Rough and StallsProblem: Engine Runs Uneven or SurgesProblem: Engine Will Not AcceleratePossible Cause Improper starting procedure usedFuel tank empty or too lowImproperly mixed fuelContaminants (water,dirt, etc in fuelFuel tank air vent closed or restrictedPinched, cut, restricted fuel line or loose fuel line connectionDirty or restricted fuel filterChoke solenoid or enrichment valve not operatingNeedle and seat in carburetor that is either stuck open (flooding) or closed (no fuel)Corrective Action Review starting procedure as outlined in Operation and Maintenance ManualCheck fuel in tank and replace or add whichever is necessaryCheck air vent on fuel tankAir vent must be open all the way and free from any contaminantsInspect all fuel lines and replace as neededTighten fuel line connectionsInspect and replace or clean all fuel filtersInspect solenoid or valve and wiringReplace as requiredRefer to carburetor disassembly in this section