BAD MISS.. thought it was the gearcase!!!

oldboat1

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Apr 3, 2002
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poss. additional corrosion from the leaking t.stat seat: starboard side electricals -- units are sealed (rectifier/regulator, power pack), but connections aren't.
 

F_R

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Somebody suggested water intrusion into the cylinders. That thought came to my mind also. Worth pulling the plugs for a looksee.
 

bob johnson

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Feb 25, 2009
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261lx7p.jpg


these are the plugs.... they don't look cleaned or washed.... they are normal for a years or mores worth of running...except the outer rust....which I determined was a slight seep out of the t stat seal........latelt when running the boat it is windy and cold...so doing that test is slightly problematic...and I procrastinate a little as I am on a mission to get someplace timely!!!.......but if it persists...ie the clean gas doesn't solve it..... then i'll do as Faztbullet suggested

bob
 

flyingscott

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Why would you not replace the plugs.Start by replacing the spark plugs. then looking at the spark plug boots see if there is corrosion in them. Then start with your coils they will usually fail when they get warm and work cold.
 

bob johnson

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I cleaned up the plugs!!!!!!! with a bead blaster at work and thoroughly cleaned them and set them...they look fine now.... If I could have found some locally,I would have bought new ones...but I get out of work at 6;30...most places are closed and there are VERY few places that sell marine plugs by champion!!!

new ones are on the way , as we speak....

bob
 

reiddo1

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I cleaned up the plugs!!!!!!! with a bead blaster at work and thoroughly cleaned them and set them...they look fine now.... If I could have found some locally,I would have bought new ones...but I get out of work at 6;30...most places are closed and there are VERY few places that sell marine plugs by champion!!!

new ones are on the way , as we speak....

bob
i had a similar issue last year with my 2000 150 hp Johnson which would not get above 3500 rpm. I read somewhere that running the overheat sensor wires too close to the plug wires could cause this problem. After reroute get the sensor wires away from the plug wires, the problem went away.
 

David Young

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Jul 12, 2015
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I really would replace the spark plugs. They look pretty worn out to me, in my opinion :).
 

bob johnson

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i had a similar issue last year with my 2000 150 hp Johnson which would not get above 3500 rpm. I read somewhere that running the overheat sensor wires too close to the plug wires could cause this problem. After reroute get the sensor wires away from the plug wires, the problem went away.

hmmmmm

Ill look at that

bob
 

F_R

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28,195
There is an obvious difference in the plug on the left end of your picture. Look at the difference in color. Something is going on in the cylinder that it came out of. Or it could be the plug itself. Whatever it is, that probably is the stutter you are hearing.
 

geoffwga1

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Aug 8, 2010
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I will follow this thread with interest until it's(hopefully) successful conclusion but for the record I am still going with the clutch dog/gearface thing.I have seen quite a few of them and even managed to fix some that are still working despite my ministrations.Lol
 

funk6294

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Apr 26, 2009
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Bob, I dont think the issue lies in the LU. I have had two outboards that have had dog clutch issues, and in both cases the motor would rev up when it slipped. On one of them (a rental boat) I ran it till the LU blew. In the rental when it was happening I had initally thought the motor had a dead miss, but it shook the back of the boat pretty violently and then after a few start and stops forward gave up the ghost all together. In all instances the motor reved up when it would jump, not sputter down as yours is in the video. I know you said you ordered new plugs, and after looking at the ones you removed I would start there. The corrosion on the exterior of the two plugs indicates they were getting water sprayed on them. The water alone could provide a path for the spark to short out, with the level of rust on the exterior of the plugs it looks like its getting a fair amount too. The most basic in any trouble shooting is to start with what doesn't look right, and those plugs do not look good.
 

geoffwga1

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Hmm! I had not watched the video before my post but I have now and I take back what i said re clutch/gear.I would say the problem is definitely electrical and those plugs should have been thrown out long since..A set of plugs is a pretty cheap fix and no matter how well you clean and dress the old ones,when they are gone they are gone because the insulation has broken down for some reason and usually there is no fix...Water in the fuel is a possibility but I think a slim one. I'm not familiar with the coil arrangement in that motor but they shouldn't be taken for granted either. good luck with it.
 

bob johnson

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Feb 25, 2009
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the more I think about the more I suspect those of you who think it might be the salt water seaping down the front of the head from the leaky t stat housing o-ring, going from spark plug to spark plug....is the culprit....I took the boat out this past Saturday and it ran fine...not a hiccup...good thing because it was blowing about 30 knots and the 3/4 mile trip down into the harbor into the wind was pretty wet....not a time to check the motor....we has a sheet of 1/8th " ice covering everything...parkas, windshield decoys...seats...you name it...I think the dog was coated in ice as well...was about 8 degrees....bob
 
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