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little help please

J

jeepthing

New member
have a 1968 100 hp Evinrude trying to bring back. rewired engine harness,cleaned electric parts, replaced cracked pulse transformer assy. only spark to the plugs is just when you stop cranking the engine.
 
Either the battery is not sufficient to crank the engine, the electric starter is dragging, OR... see the following:

(Voltage Drop To Battery Capacitance Discharge)
( Pulsepack When Electric Starter Is Engaged)
(J. Reeves)

On the older Battery Capacitance Discharge ignition systems (1968-1972), the electric starter reaches a point, even with a top notch battery, whereas the starter will draw excess voltage/current/whatever which results in a voltage drop to the pulsepack. The cure is to purchase a diode which is capable of handling 12 volts and installing it between the starter terminal of the starter solenoid (NOT the battery cable terminal) and the wiring terminal that supplies voltage to the pulsepack.

The diode must be installed so that the current flows from the starter terminal of the solenoid to the pulsepack... NOT vice versa. When that diode is installed in this manner, when the key is turned to the start position, the voltage that is applied to the starter is also applied directly to the pulsepack via the diode effectively eliminating the voltage drop and energizing the pulsepack with the required voltage needed for its proper operation.
 
Thanks Joe for your reply, hopefully you have time for part b of question A. Having reviewed your answer I tryed to locate the 12 volt diode, here on this site,auto parts stores and radio shack. Is there some unit you have in mind. Not finding anything thing to retro. Thanks again...
 
jeepthing said:
Thanks Joe for your reply, hopefully you have time for part b of question A. Having reviewed your answer I tryed to locate the 12 volt diode, here on this site,auto parts stores and radio shack. Is there some unit you have in mind. Not finding anything thing to retro. Thanks again...
Click to expand...

They're available at any Radio Shack store. You just need to spell it out for some of those fellows working there. NOTE that it is NOT one of those small diodes that one would use in a circuit board. You need one that would hold up under 12 volts as supplied via a automobile battery... sort of looks like monkey nuts with two wires leading from it. I've bought them at Radio Shack to use as I've explained... also used them on some electrical powered lawn equipment (Weed Whackers).
 
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