# Help, please! Johnson ouboard runs rich & below WOT



## dgodek (Apr 5, 2012)

I have a '95 Johnson 88 SPL that is running rich and only at 3,000 to 3,500 RPM at WOT. Occasionally, the RPM will increase to normal and the boat runs like it should then slowly goes back to running poor and below WOT. The motor seems to perform underway at low RPM as it should. Choking the motor while underway has no impact on its operation.

After the first time having these issues, I took the carbs apart and cleaned them. No new carb kit was used. The spark plugs are new. The gas is pre-mixed 50:1 at the onboard fuel tank and is less than 6 months old. Sea Foam has been added. The fuel lines between the tank and motor are new. 

After the cleaning, on land with muffs on, started easily, reved as it should with the warm up lever up and throttled correctly above WOT when the shifted into forward gear. It then started at the dock eaily, too. But once back on the water, the motor still tops out way below WOT and after running a while, the motor gets tough to restart without using the warm up lever. I assume this is because the plugs have became fouled again while underway.

Also, there seems to be a small build up (streak or glimmer, not puddle) of fuel on the top of the bottom carb since its recent cleaning. When I saw this back on dry land, I squeezed the primer bulb a bunch so it's really hard but no fuel leaks out.

Should I be looking at a float issue, a "true" carb rebuild with new parts? What?

Alternatively, is there someone in the Mentor area who you'd recommend have a look at this or fix it?

Thanks, Dave


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## KaGee (Sep 8, 2006)

Don't just throw parts at it. You'll find yourself spending more than at a shop.

It could be carb related but could also be timing advance or power pak. Not an easy problem to diagnose on a forum.

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## MassillonBuckeye (May 3, 2010)

Sounds like a bad coil. Test your spark on each cylinder. Use a spark gap tester and not one of the lighted plug testers. A bad coil can light up a cheap tester, but still not have enough umph to jump a proper gap.

Pull the plugs after running it for a few minutes. Do you see unburnt gas on any of the plugs?

Pull both plugs, get one of these and set the gap to 7/16" and ground it to the block and hook your plug wires to it one at a time and crank. Seems like a big gap, but thats what you need to jump for proper fire.
If no spark, then you may have a bad coil or powerpack.










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## turkeyt (Apr 13, 2006)

MassillonBuckeye said:


> Sounds like a bad coil. Test your spark on each cylinder. Use a spark gap tester and not one of the lighted plug testers. A bad coil can light up a cheap tester, but still not have enough umph to jump a proper gap.
> 
> Pull the plugs after running it for a few minutes. Do you see unburnt gas on any of the plugs?
> 
> ...



MB. Kind of sounds like motor is not running on all cylinders which it will run smooth but at half power. That power pack will act up like a coil going bad. I had a bad power pack and the way i checked it was flip the wires to the coil to see if the spark followed the wires and it did. That's if the the coil is good. They go hand in hand and i had an extra good coil i put on and it changed nothing. Check the power pack first or have it checked, as they usually go bad first.

That power pack puts out some juice and takes a different meter to check it at the shop. If you can get it to act up on muffs then you can check it. Electronic and fuel issues are time consuming to check. If the spark checks out then i would go to the carbs next. Just a thought. MB, Get that boat cover fastened down??


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## MassillonBuckeye (May 3, 2010)

You talking about a DVA meter/adapter? Yeah, output voltage is around 600v on these old mercs I have, not sure about his motor. The DVA meter has a big capacitor in the circuit which holds those very quick bursts long enough for your meter to measure accurately. I actually homebrewed one myself(too chicken to try it!!) and ended up buying a DVA adapter that fit my volt meter from maxrules.com <--- awesome old outboard parts/diagrams website!! which I still haven't used.. lol. Gotta get spark first. If your spark can jump the 7/16" gap, then move to the other stuff. I started out with one of the Xenon inline spark plug testers and my coil was putting off enough juice to light it up so I thought it was OK. Well, I did some research and learned those things are pretty much worthless and went for the gap test and VOILA, no spark. Moved the coil to a different lead on my switchbox and NO SPARK. Tried other coil in both positions and had spark both positions. So bad coil it was. I got a whole used electrical system off a newer compatible motor for a steal on Ebay. So I'm ready if any of the other coils, stator, trigger, plug wires or switchbox goes bad! lol

Yeah, I got the cover buttoned down pretty good but it leaks like a sieve! I'm going to end up draping another HF tarp over it until I can afford a custom cover I think. Not real impressed with this Sharkskin stuff, but it should be ok for light duty and quick stuff. Trailering should also be fine.


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## dgodek (Apr 5, 2012)

Thanks to everyone who posted advice. Much appreciated though it's taken some time for me to act on your suggestions. It turns out I've lost a cylinder. Three of the four measured 120# while the top right measured 30#. I've not pulled the heads yet...

So, I'm back with a new question: doubting there is an easy fix, where do I get a good 1995-vintage 88, 90, 112 or 115 hp Johnson power head? Or, is it worth trying to rebuild the motor vs. buy an entirely new outboard?

I've found a complete rebuild parts kit online for about $600. Can a guy with some basic tools and familiarity with motors tackle the job along with a good shop manual?


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## UFM82 (Apr 6, 2004)

You've lost compression on the cylinder. Now you need to see why. Head gasket? Cracked head? Melted piston? Scored cylinder wall? Broken rings? There are a lot of things that could have happened and some are terminal. You're not going to rebuild an engine with a badly scored cylinder. Not only do you need to find out what happened you need to find out WHY it happened. Did a cylinder go lean and melt the piston? Did a chunk of carbon break loose and score a cylinder, cause a hotspot and melt a ring land? Or did you merely blow a head gasket and it's a simple fix? 


If you pop the head off and see big time damage, start looking for another engine. It'll cost more to fix than to replace. One of the beautiful thngs about 2 -strokes is how easily the heads come off. 
UFM82


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## KaGee (Sep 8, 2006)

I would investigate what your problem is first and go from there.


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## captk (Mar 13, 2008)

Like UFM82 said pull the heads and take a look. take pics and post if you need a second opinion, I am leaning toward blown head gasket. but???


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## dgodek (Apr 5, 2012)

Pulled the head off the right side of the motor last night. If my problem were "only" a blown head gasket...seems the rings disentegrated into pieces and the piston pressed them into the head. The cylinder looks nice: minimal, if any, scoring and the cross-hatches are still visible. The bottom cylinder and head are in perfect shape.

Should I rebuild or use this as an excuse to repower?


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## UFM82 (Apr 6, 2004)

That's major. You'll need to pull the powerhead and split everything anyway to put a new piston in it, assuming the cylinder isn't egg-shaped. And you'll find other things to replace while you're in there. Add up the needed parts ( piston, rings, rod bearings, etc) and then the other stuff you'll find once you're there and I bet you'll crack the 1K mark pretty quickly. You can find a decent outboard with controls on CL or eBay for that kind of jack. 

And don't forget- even if you rebuild the beast you still don't know why it did it. If the top land is gone and that allowed the rings to come apart you went way lean or overheated that cylinder. Why did it happen? You need to determine that or the same thing could easily happen to the fresh engine when you get her back up and running. 

I'd start buttering up the wife for the new engine you are going to buy.


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