2005 Polaris Sportsman 400/500 Service Manual, Page 112Get this manual
SPARK PLUG FOULING
S 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
Dead battery Starter motor does not turn Engine seized, rusted, mechanical failure Engine Runs But Will Not Idle Restricted carburetor pilot system Carburetor misadjusted Choke not adjusted properly Low compression Crankcase breather restricted Engine Idles But Will Not Rev Up