2003 Polaris ATV Trail Boss 330 Factory Service Manual, Page 194Get this manual
ELECTRICAL
IGNITION SYSTEM TROUBLESHOOTING
No Spark, Weak or Intermittent Spark
No12 volt power or ground to CDI Spark plug gap incorrect Fouled spark plug Faulty spark plug cap or poor connection to high tension lead Related wiring loose, disconnected, shorted, or corroded Engine Stop switch or ignition switch faulty ETC switch misadjusted or faulty Poor ignition coil ground (e.gcoil mount loose or corroded) Faulty stator (measure resistance of all ignition related windings) Incorrect wiring (inspect color coding in connectors etc) Faulty ignition coil winding (measure resistance of primary and secondary) Worn magneto (RH) end Crankshaft bearings Sheared flywheel key Flywheel loose or damaged Excessive crankshaft runout on magneto (RH) endshould not exceed .005 Faulty CDI module
Test output from the CDI and pulse (trigger) coil and compare to the tableThe following measurements are obtained when cranking the engine with the electric starter, spark plug installedThe starter system must be in good condition and the battery fully charged200 Watt Stroke DCCDI Ignition Test Connect Meter Wires To: Yellow Blue and Ground YellowRed and Yellow Reading (Without Peak Reading Volt meter) 20 DCV 3.3 DCV