74 evinrude 9.9 misfires/kicks hard

[Brider]

I have been browsing posts on here for the last few months as I got my 12’ tin in fishing shape, this is my first time posting.

I have a 74 evinrude model 10424S. The motor idles well but occasionally at half to full throttle it kicks hard repeatedly. It seems as if it is possibly misfiring, cutting out then instantly back on. I have new NGK BR6HS plugs gapped at .030. The coils each have a small crack on the side and the spark plug boots don’t seem to have a very tight connection to the plugs, but I am not sure if this could be the issue. Father in-law had this motor for 20 years before me and said he never had this issue although it sat the last 5 years or so.

Any help would be appreciated.

 

[Pappy]

Cracked coils will leak spark to ground. Either remove and reseal them to the best of your ability or replace them and give it a try.
When removed look at the areas of the coil that are close to the block of the engine. Should see a burned spot on the coil if it is cracked back there.

 

[RAMROD]

+1^^^ the one I replaced had a burn stop and a pine hole in the middle.

 

[Captain Ahab]

Start by replacing the coils and wires

 

[Brider]

Thanks for the tips, I will pull the coils out this weekend, no burn spots on the visible sides but could be on the back out of sight. Guessing I wont find any replacements local and will have to order online.

 

[Pappy]

If you have a Johnson/Evinrude dealership close by please try and support them. Just about guarantee they will have the coils in stock for your engine.

 

[Brider]

I wish I had a dealer close by with the parts, but seems that because Lake Tahoe does not allow two-strokes no one has anything. One shop 45 minutes away had one coil . Just ordered what I needed from marine engine.com.

May be a stupid question but does it make a difference with the wiring for the top and bottom coil or is it just a simple part swap type replacement. I purchased the sierra marine part. https://www.marineengine.com/newparts/part_details.php?pnum=SIE18-5196&ptype=&Engine=&Model=

 

[sr71]

Brider » Yesterday, 20:47[/url]"]I wish I had a dealer close by with the parts, but seems that because Lake Tahoe does not allow two-strokes no one has anything. One shop 45 minutes away had one coil . Just ordered what I needed from marine engine.com.

May be a stupid question but does it make a difference with the wiring for the top and bottom coil or is it just a simple part swap type replacement. I purchased the sierra marine part. https://www.marineengine.com/newparts/part_details.php?pnum=SIE18-5196&ptype=&Engine=&Model=

Simple part swap replacement....duplicate wiring and coil position from old setup, and sand the new coils where the wires attach.