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Help wanted.. 1996 60 horse johnson running rough won't go over 7 mph


Tim G.

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looking for any pointers on solving my issue. Last Saturday  I put in reservation gas. Then the boat would stall out while trolling. When I picked up a moved I realized the boat would only go 7 mph not 30. I suspected fouled  plugs. Changed them and ran well tol fouled again. Next day I removed all gas. And changed the plugs .was running back to normal. Fast forward to yesterday and she was running rough again. Changed plugs. Ran seafoam though a gallon of gas. Sprayed carb cleaner in carbs. One plug seems to foul out more then others so I concentrated  on that carb. Took it off.  Cleaned it and put it back together. I did not pull out the needle cause I didn't have a replacement  yet in case I lost a piece. Still running bad. I have spark at all three plugs. Sounds like too much gas or maybe air in the line somewhere. But why did it run good sunday but not today.  Uhh 

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Check your gas lines a pump bulb. Mine had all kinds of problems low power. Was getting to much oil and making it foul plugs run bad drop a cylinder. And this is what fixed it ..the gas line had broke down and it was collapsing making the engine starve for fuel but since it's oil injected and it works off vacuum it was drawing extra oil. Here is how the line was it had a liner and it came loose and was collapsing. This was the piece between the fitting on the boat and the primmer bulb. I just replaced all the lines and bulb now it runs perfect IMG_20200710_103626956.jpeg

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Start simple , clean all electrical contacts use dielectric grease esp. the ground behind the power pack : if you can run the engine in the dark looking for sparks ! I found out the hard way , thought it was the carbs took all afternoon to do a rebuild got late started the engine same problem , by now dark saw spark behind the power pack just had to tighten the bolt , fixed it !

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If that motor has 3 carbs like my old 55 Johnson it could be a few issues 

 

The rich / lean screws are in to far and it won't switch over from the adjustable low speed to the non adjustable high speed.  Or clogged jets . 

 

Mightily be running on one cylinder because of  a carburetor

 

Bad coil.  or spark amplifier . 

 

But if it was,running good  before you got new gas , I would say fuel or carbs . 

 

But what do I know ? 

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Its a 2 stroke . I have ran new gas through a small can , changed plugs. Rebuild all three carbs, changed the gas line from tank to motor. Checked the smaller lines for blockage. I definitely  want to check the exhaust  for blockage next and if thats not it I'm suspecting an electric issue 

Edited by Tim G.
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Its a 2 stroke . I have ran new gas through a small can , changed plugs. Rebuild all three carbs, changed the gas line from tank to motor. Checked the smaller lines for blockage. I definitely  want to check the exhaust  for blockage next and if thats not it I'm suspecting an electric issue 

What color are the spark plugs?


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When it cuts out, does it get to full rpm? Meaning, if wide open throttle is 5400 rpm, does it get there or die at 2500? When I bought my mercury 60hp 2 stroke used, it only got to a certain rpm. Then it quit. Ended up being an electrical issue. Bought a new piece and it was good as new. I'd have to look back at what the issue exactly was. 

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If it has the same ignition system as mine and a lot of others I know had  similar problems , i would say it is that . 

Those motors are notorious for that . My guess , the spark box . 

 

A 96 is not that old if it doesn't  have a lot of hrs on it .

 

I screwed around with mine for a long time and then sold it . 

 

Might not be a bad investment to bring it to someone who knows . 

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Ditto on HB2 ! OMC = outboard marine crap ! If you mean power pack that can be changed did it X2 on my 1983 70 hp which is still my main outboard on my Starcraft ! Even with the service manual from OMC I could not figure out how to test it , so I just changed it X2 and still runs ok for now ! If I live long enough the next engine will be a Yamaha !

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I have 3 coils. Did I bench test with n ohm meter. Had the same reading  on all three. I definitely  have spark  but maybe just not timed right.  I've eliminated all gas issues and carbs. I got a manuel and testing  requires all these make shift tools and meters 

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  • 2 weeks later...

Shop said that it overheated when the impeller went and caused internal damage.  He invested  alot of time into it and stopped because  he new it wasn't an easy fix and didn't  want to spend anymore time on it. Only charged me 100$. Im not convinced though that it's internal  damage because  there is no way in hell it would go from running bad to running great the next day to back to bad the next weekend if that was the problem.  Second opinion  is next to do 

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