2003 Polaris ATV Trail Boss 330 Factory Service Manual, Page 90Get this manual
SPARK PLUG FOULING TROUBLESHOOTING
G Spark plug cap loose or faulty Choke cable adjustment or plungercable sticking Foreign material on choke plunger seat or plunger Incorrect spark plug heat range or gap Carburetor inlet needle and seat worn Jet needle andor needle jet worn or improperly adjusted Excessive carburetor vibration (loose or missing needle jet locating pins) Loose jets in carburetor or calibration incorrect for altitudetemperature Incorrect float level setting PVT system calibrated incorrectly or components worn or mis-adjusted Fuel quality poor (old) or octane too high Low compression Restricted exhaust Weak ignition (loose coil ground, faulty coil, stator, or ETC switch) ETC switch mis-adjusted Restricted air filter (main or pre-cleaner) or breather system Improperly assembled air intake system Restricted engine breather system Oil contaminated with fuel Restricted oil tank vent
Engine Does Not Turn Over
G Dead battery Starter motor does not turn Engine seized, rusted, or mechanical failure Recoil components damaged