1978 Johnson 55 HP Outboards Service Manual, Page 39Get this manual
Current flowing through the No1 ignition coil primary winding produces large magnetic field surrounding the secondary winding and produces the high voltage to the spark plug, igniting the fuel in the engine cylinderWhen SCR#2 is triggered, the capacitor is discharged through the No2 ignition coil primary windingCurrent flows through S.C.R#2 and returns to the other side of the capacitorThe No2 ignition coil then produces the high voltage to the spark plug to ignite the fuel in the other cylinder IGNITION STOPKILL CIRCUIT (See Figure 4-5 Since the capacitor is the "heart" of the ignition system, the stop button (or key switch) is used to prevent capacitor chargeOne end of the capacitor is connected to engine groundThe key switch when closed will connect the other end of the capacitor to engine groundWhen both ends of the capacitor are connected to engine ground, current flow from the charge coil will by-pass the capacitor as shown in Figure 4- 5When the capacitor is not "charged," ignition calIDot occur