Odd Outboard Behavior

[Coherence]

Hey guys, 

 

I am no mechanic or even really mechanically inclined by any means, so I figured I would ask around here and see if anyone can help me identify a strange issue my old 2 Stroke Evinrude is having. Mind you this motor is from 1986, and is a cantankerous little machine - noisy, loud, and ugly as sin. 

 

When I shift into forward and am travelling below about 60% throttle the boat intermittently 'kicks' forward almost as if I have bumped the throttle up real quick then it seems to drop out of gear, before catching back up to the set throttle speed. It's definitely a strange action that occurs every 45 seconds or so. When travelling on plane at full speed this issue does not occur at all, and the ride is normal, with no kicking. 

 

Any thoughts? I'm not sure if this is a motor issue, a throttle cable issue, or something else entirely.

[Jig Man]

I am by no means a motor tech but it sounds like a fuel problem to me.

[WIGuide]

x2 on the fuel. Also, when is the last time you changed the plugs? Do you run any fuel stabilizer in it? Are the plugs gapped correctly?

[Al Wolbach]

Before I did anything else I would run a can of Seafoam through in to see if that may clear it up or improve it...

[slonezp]

Way2slow is who you want to ask

[Way2slow]

From what you describe, it sounds like it's dropping a cylinder and then goes back to running on it on an intermittent basis.
Now, what's causing it to do that could be a number of things.
The carbs have three different fuel delivery stages in them, low speed/idle, mid range and high speed. Could be a dirty carb causing delivery problems in the mid range or fuel pressure issues in the mid ranges.
Then there's the ignition system where the are a whole host of things that can cause it.
Intermittent problems sometimes require considerable trouble shooting and since you don't have a Dino or test tank, that means having to do it at the lake and preferably with a test prop.
If you start just throwing stuff at it, it can get very expensive.
My first step would be to replace the spark plugs, next would be to clean the carbs, which for me is just a couple hours of my time, for you it's could be a couple hundred dollars, and that could be money ticked away.

[JayKumar]

+1 on Sea Foam Motor Treatment -- in gas, in oil, maybe fog it and leave it for a bit too

[Choporoz]

I'm no help.  Just here to wish you luck.  I got my father's old '76 Johnson 6 this year and started having lower unit problems soon after I got it running.  I'm not mechanically inclined, either.  Every shop I've called....first question from them is "does that motor have sentimental value?"

 

Good luck!