Johnson Evinrude Outboard Motors 1956-1970 1.5-40hp repair manual., Page 164Get this manual
IGNITION
may be cranked manually and the engine startedThe flywheel-type magneto unit consists of an armature plate, and permanent magnet built into the flywheelThe ignition coil, condenser and breaker points are mounted on the armature plateAs the pole pieces of the magnet pass over the heels of the coil, magnetic field is built up about the coil, causing current to flow through the primary windingNow, at the proper time, the breaker points are separated by action of cam, and the primary circuit is brokenWhen the circuit is broken, the flow of primary current stops and causes the magnetic field about the coil to break down instantlyAt this precise moment, an electrical current of extremely high voltage is induced in the fine secondary windings of the coilThis high voltage is conducted to the spark plug where it jumps the gap between the points of the plug to ignite the compressed charge of air-fuel mixture in the cylinder5-6 TROUBLESHOOTING Always attempt to proceed with the troubleshooting in an orderly mannerThe shotgun approach will only result in wasted time, incorrect diagnosis, replacement of unneccessary parts, and frustrationBegin the ignition system troubleshooting with the spark plugs and continue through the system until the source of trouble is locatedRemember, magneto system is selfcontained unitTherefore, if the engine has key switch and wire harness, remove them from the engine and then make test for