1968 85hp Evinrude Electric Shift not getting spark on plugs

[JohnD90472]

I have tested the amp and coil, I am getting 349 volts from the amp when the shaft rotates.When I rotate the shaft to the point it should fire, I am not getting it to the plugs. If I disconnect the blue wire from the amp to the coil and rotate the shaft to the point of firing then touch it to the coil, it sparks at the plug. I disconnect the blue wire and rotated the shaft and touch the blue wire to the coil each time,I get spark on each plug. What could be the problem causing it not to spark when connected and starting?

 

[JB]

Re: 1968 85hp Evinrude Electric Shift not getting spark on plugs

Howdy, John. That engine uses an unusual breaker point timed, CD ignition system. Your symptoms suggest either an electronic module (amplifier) shorted output thyristor or signal from the points (2 sets) not controlling the amp. If the 349volts you measured at the blue lead is constant, you cannot pulse the coil. The coil cannot turn DC voltage into pulses to the plugs, it needs 300-400volt pulses to make 50Kv pulses to the plugs. This is demonstrated by what happened when you removed, then touched, the connection. This could happen if the thyristor is shorted, or if erroneous signal from the points has it turned on all of the time, rather than pulsing it at correct times.<br /> <br />The Black/White stripe wire into the amp comes from the points, which are located under the distributor. Set new points at .012, old ones at .010. With ignition off, use an ohmmeter to verify that pulses are getting to the amp when the shaft turns.<br /><br />I realize this is hard to visualize from words. If you need it, maybe I can figure a way to Email you selected parts of the manual.<br /><br />Because I only live about 30 miles from you, it might be easier to just lend you the book.<br /><br />Let me know what happens.<br /><br />Red sky at night. . . .<br />JB

 

[JohnD90472]

Re: 1968 85hp Evinrude Electric Shift not getting spark on plugs

Thanks for your reply. I forgot to tell you that when I put my meter on the blue wire and rotate the shaft I get the 0v then 349, then 0v, then 349v, then 0v, and so on. It is pulsing. That is why is in confusing me.

 

[JB]

Re: 1968 85hp Evinrude Electric Shift not getting spark on plugs

Hmmm. That is confusing. It seems that something is preventing the rise time of that pulse from firing the plug, yet, if you supply the fast rise time pulse by opening and closing the blue wire the plugs fire.<br /><br />I still suspect the thyristor in the amp, though I am less certain than I was last night. The points seem to be turning the 350 volt circuit on and off, charging the capacitor, and the coil turns a fast rise pulse into spark at the plug. It could still be a shorted thyristor. Unfortunately, the manual assumes we are wrench-only techs and doesn't give us any electronic innards data on the amp except to admit that it is a CD system, but they are pretty much the same from one early system to another. Built a couple from scratch before they could be bought for retrofit.<br /><br />I would try to borrow an amp or buy one on a return-if-it-doesn't-fix-it deal.<br /><br />Good luck, and let us know what happens.<br /><br />Red sky at night. . . <br />JB

 

[JohnD90472]

Re: 1968 85hp Evinrude Electric Shift not getting spark on plugs

JB, no one around here has an amp, but they say they can order me one at the cost of 298.00, and no return on electrical parts.<br />Doesn't that stinks, oh and I also have a manual. I am an Electronic Tech, I figured it might be the amp, but the fact that it was pulsing threw me.I tried to get some charts for the amp, but they wouldn't sale them to me. I guess you have to be a dealer or repair shop.<br />If it is the amp, I am out of luck. I can't afford that cost.<br />Let me know if you think of anything else, Please.<br />John

 

[Walter]

Re: 1968 85hp Evinrude Electric Shift not getting spark on plugs

John...JB:<br /><br />I know virtually nothing about this engine, but my buddy owned a '69 Johnson 115. His engine had what I remember him calling a power-pack. Is it safe to say John's engine isn't equipped with one? I don't recall ever messing with points on my bud's engine...I thought the power pack was in lieu of points, etc...<br /><br />Walt

 

[JB]

Re: 1968 85hp Evinrude Electric Shift not getting spark on plugs

Hey Walt. John has one of those transitional engines. They used CD (capacitor discharge)to encourage the coil to fire the plugs, but still used points to establish timing and trigger the thyristor to Discharge the Capacitor. For '68 it was state of the art.<br /><br />Red sky. . . . <br />JB

 

[JohnD90472]

Re: 1968 85hp Evinrude Electric Shift not getting spark on plugs

I talk to my repair guy and he has an old 1968 85hp Johnson electric shift sitting around. It doesn't have the amp or coil, but he said he would sale it to me for parts for $200.00. I am not sure about it.<br />What do you think JB?

 

[JB]

Re: 1968 85hp Evinrude Electric Shift not getting spark on plugs

If you are going to fix and keep the one you have, John, it certainly seems like a good source of parts. <br /><br />Call Twin Cities Outboard in Minneapolis about your amp. They just might have one for less than the $300 quote you got. There are also a few shadetree operations around DFW that might have one, but I haven't prospected for parts in several years and forgot exactly where they are.<br /><br />This "amp" can't be very complex. It's gotta have a multivibrator (easy, girls), a step up transformer and a rectifier system to make your 350vdc to charge about a .01ufd capacitor. Then it's going to have a thyristor, probably an SCR, to discharge the cap through the coil primary when it is triggered by the points. If you are very lucky it isn't potted and you might be able to get access to the components inside.<br /><br />At the library you can probably find an electronics project book from the 60s that will have schematics, etc. for a home-made CD ignition system for a car that is triggered by points. Between that and what you've got you might be able to put together something that will work for a lot less than $300.<br /><br />Another option is to investigate converting the whole ignition to the later, pointless, CD-4 system for which there should be plenty of used parts about.<br /><br />Finally, consider repowering with a mechanically shifted later model engine.<br /><br />That ought to be enough options to give you an overheated brain for a while. If I think of anything better, I'll post it.<br /><br />Let me know what you decide to do and how I can help.<br /><br />Red sky at night. . . . <br />JB

 

[clanton]

Re: 1968 85hp Evinrude Electric Shift not getting spark on plugs

I looking at a diagram that says min voltage at red or purple wire at pack when cranking is 9 1/2 volts. Then says remove wire white/black from points touch ground should fire. I have OMC trouble shooting guide for this system will try to find it. Try RAY at 256 772 3829, He will help you if not busy.

 

[clanton]

Re: 1968 85hp Evinrude Electric Shift not getting spark on plugs

I looking at a diagram that says min voltage at red or purple wire at pack when cranking is 9 1/2 volts. Then says remove wire white/black from points touch ground should fire. I have OMC trouble shooting guide for this system will try to find it. Try RAY at 256 772 3829, He will help you if not busy.