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1984 90hp Johnson outboard

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drdodd

New member
Help...
I recently picked up a problem with my*1984 90hp johnson. I was up at the lake, I*launched the boat and it*start like always, drove to the dock, parked it and left it til the next day. when I went out the next morning, it*started right up, I*drove to the *gas dock turned it off, fill the tank, started again normaly, took it out on the lake to blow the dust out since it had been about a month since it had run.*I ran it wide open for about 15 mins.*I saw a friend so I pulled up and turned it off, we talked for about 5 mins. then the boat would'nt start, turned over and cranked but would'nt start, so he started towing me in, after about 45 mins. tried again and it started right up and ran fine. Took it*back to the dock turned it off and tried to start it and it would'nt restart again, after about an hour tried again and it started and ran great. the next day same thing happened, no matter how long I run, it runs great but will not restart for at least 45 mins to an hour. Does anybody have any ideas what this could be??????? I assume it isn't getting any spark??? but haven't been able to check it.
*:confused:
 
First thing I would do is remove the engine cover and give every coil and powerpack a thorough visual inspection. Look for any cracks on these components. Also get a flashlight and look at the stator and timer base under the flywheel to see if there is any melted goo.

If these all look fine visually, get a spark tester. I'll be you are correct that you are losing spark, but it's best to have a tool to confirm things with measurements rather than guessing. Take the boat out for a decent run the shut it off and start checking for spark on each cylinder.

For quite a while I battled a similar problem with my '79 Evinrude 140. It seemed like it would run just fine but once I shut it down it was a monster to restart. Then, once it did start it would spit and sputter and die when taking off. I would have to set for about 2 minutes at high idle to 'clear it out' before I could take off.

At the end of last summer I finally solved the puzzle.
1) My coils were overheating
2) I had cracks in one coil and poor spark in another.

When I rebuilt the engine in '04 I removed all the tattered foam in the motor hood and installed some nice dense stuff all over to deaden the sound. It turns out that wasn't the best idea. The foam was resting right on my against the coils and flywheel. My theory is the foam was acting too well as an insulater and was causing heat to be held in the coils and flywheel when I turned off the engine. So, rather than cooling as the motor sat they just kept absorbing heat and were breaking down. I cut away all the foam that had been contacting these parts.

The other part of the puzzle was I found a huge crack in the top starboard coil. I replaced that coil and it still didn't run real great and was goofy starting when hot. Spark was weak on the lower cylinder so I'm guessing it's possible the crack allowed the top coil to arc over on the lower coil and cause damage. At this point I decided to punt and just install new coils on each cylinder. The 2 port coils were original to the engine and I figured if the starboard ones had gotten that hot from the insulation it's possible the port ones weren't in very good shape either.

After doing all that the boat ran like a champ, it would start on the first try, hot or cold, and gave me excellent acceleration and power.

KJ
 
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If the stator under the flywheel is dripping a sticky looking substance down upon the timer base and powerhead, replace the stator.

That melt down scenario results in a voltage drop to the powerpack's capacitor which in turn results in weak, erratic, and eventually no ignition. Some function fine when cold but when hot.... as in sitting after running, engine heat rises up to that area.... the ignition fails until it cools down somewhat. Eventually even the cool down period is of no avail.
 
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