1991 Johnson/Evinrude Models "EI" 40 thru 55 Service Manual, Page 115Get this manual
Principles of Operation Flywheel f'1l The flywheel contains permanent magnets which energize L!J the charge coil, ignition module, and alternator statorOnce the flywheel exceeds minimum cranking RPM, the flywheel's magnetic lines of force pass through the ignition plate components to produce voltage in those circuitsThe flywheel must be in good condition and correctly located to ensure proper ignition timing and sufficient charge coil outputCharge Coil
rv The chargemetal laminationmany windings of wire wrapped coil consists of around Once the flywheel exceeds a
minimum cranking RPM, the flywheel's magnetic lines of force pass through the charge coil windings to produce approximately 300 volts of alternating currentThis voltage is supplied to the ignition module to operate the system Ignition Module The ignition module
has six basic functions :
The ignition module receives the charge coil output and converts it to direct current The ignition module stores direct current in capacitor The ignition module has an internal coil that controls ignition timing by sensing flywheel magnet position The ignition module directs the capacitor output to the ignition coil primary windings through series of electronic switches (SeR's)The SeR's select the correct ignition coil primary winding by sensing the polarity of the sensor coil output The ignition module incorporates the S.L.OWTM warning system which gradually limits engine speed to approximately 2000 RPM if engine temperature exceeds 2030 (950 e)Once the S.L.OWTM warning system has been activated, the engine must cool to 1620 (72 e) and the engine must be slowed to an idle before normal operation can be resumed The ignition module has an RPM limiting circuitThis circuit helps protect against powerhead failures caused by excessive RPM operationSome causes of excessive RPM include underpropping, excessive wear to propeller blades, ventilation of propeller, improper motor installation, and unusually light loadU