intermittent outboard issue

After a series of weekends with other task demanding priority, I got out there today and after a few minutes the rpm dropped off to 2500 again. Some quick spark plug leads 'analysis' revealed that I was only running on the starboard bank. Points me toward CDI power pack or fluky connections to/from same. I'll get it in the shop tomorrow and put my meter to work, see if I can narrow it down from there. I guess switching power packs to opposite sides could reveal details too.

Thanks to all who replied, I will also check out that fuel leaking when tilted forward.
 
Sly Just read your first post, guess I get a failing grade, as I just see that indeed you stated 1980.
I had a 1988 80hp merc that would slow down when it over heated and hoped yours also did that,
and that would be an easy fix. Sorry, ....BB
 
I know on the Yamaha if 2 cylinders loose spark it is a trigger coil that has failed. Not sure if your engine is configured the same way.
 
These engines have a CDI power pack for each bank. Port side and starboard side are two identical ignition systems. If 'trigger coil' is Yamaha's term for power pack, then you're right. I was short on time today, I'll get in the shop tomorrow and go through the meter checks for the power pack as spelt out in the shop manual.
 
No its not your power pack/spark. I just read you say you have gas coming out when you lift your leg. If you lift that leg up and fuel is coming up. It's fuel delivery.... Your getting way to much gas mixture in... I know this because when I first got my old boat I used to not bump key I would push it in continuously and start....And it would flood. Same thing I would lift leg and gas came out. You only need to push in a few time to get gas in carbs at start up. If you give it and don't warm engine up it could bog down too.

I would rebuild the carbs, and make sure I believe there is a float that can get stuck.. There is another thing that can screw you. There is a red lever ( manual choke) on engine I can't remember what position it is in. If that in wrong position it will flood your carbs.

Just suggestions...

.
 
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Again, start with the simple stuff. clean connections and good grounds. Test the ignition kill circuits I believe they are the yellow/black wire, maybe one of the power packs is getting a ground signal and turning off. Or swap them and see if the spark drops on the same side. I would then move to the trigger. Leaking fuel out the front of the carb is SEMI normal when tilted fully up but it should stay inside the air intake housing. There should be a drain/hose in the bottom of the intake to take that fuel and route it into the engine. If the gasket between the air intake and the carbs is old/saturated it will leak, not a big deal and shouldn't effect the engine in the upper rpm range. If its getting fuel but not reaching rpm it has to be electrical.....or compression. Suck, squeeze, bang, blow. Have you checked the compression?
 
If you have no spark then you will have raw fuel coming from the leg as it isn't being burned in the cylinders not firing. When I first saw this post I suspected ignition issues. If you confirmed no spark on one side when it was acting up then stick with that direction to solve. Intermittent issues are more often electrical in nature and diagnosing can be difficult because you have to evaluate while it is acting up...which it will never do when it is in the shop!!! lol
 
My old boat had a 1987 225 looper. Two power packs and a vro. I became an expert with this model. Intermittent power happened to this engine at times. Running it at 2500 to the point where it is warm I would stop the boat and take off the hood and check the temperature of the cylinders. If one side was colder than the other I would suspect the power pack on the cold side. This method is difficult to be sure. Later I bought an inductive tachometer. This tool was invaluable for this and other problems with the ignition system. Corrosion messes with the flow of electricity and it will cause the electronic switches in the power pack to fail. That is why everything downstream of the power packs must be free of corrosion. That means the coils and their connections to the plugs and the plug wires. Also the spot where the coils ground out to the block must be free of corrosion. Emery cloth and little grease in the boots of the coils cleans this problem up. Other electrical problems related to corrosion was the shift interrupt switch going bad. I also had a timer base go bad. Everyone else calls these the trigger. The timer base was shorting out so it was putting spark to plugs at the wrong time. The motor would run fine on the hose in the driveway but not much power in the water. I used the inductive tach and a timing light to figure out this problem. Had to index the flywheel which means mark the top dead center for each piston and use white paint and mark each cylinder number on the flywheel with with paint.

The last story is where the motor would suddenly drop 2000 rpm and then get it back. Rpms would go from 2500 to 4500 and then back again without warning. This problem was intermittent and could only be observed on the water. I took it to two different shops and after a hefty bill from both of them I decided to do caveman mechanics on it. Both shops had followed the diagnostic procedures in the shop manual and came up with nothing. One even ran it on the water. Out desperation I started taking everything off the motor. When I got to the vacuum hose that connects to the pulse limiter that the vro uses to get its crankcase vacuum from I found out the funky fifty cent plastic hose clamps that Evinrude used was loose and that the vacuum was breaking and the vro was working fully and then not. This problem was very intermittent and was something that some good mechanics could not find. It's not in the book.

Most of the problems on these engines is related to corrosion but not everything. The shift interrupt switch is only mentioned in passing in the book but not as something to look at in the troubleshooting section. This is why I said before to be methodical in diagnosing the problem. Don't assume anything.
 
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1. No spark on port side.
2. Swapped power packs to opposite sides.
3. Now no spark on stbd side.
4. Replaced faulty power pack, $100.
5. Problem did not return on short water test, 15 minutes mostly WOT.

I will put some more time in this week in the shop, cleaning and greasing ignition system electrical connectors and grounds. Things look reasonably good but 34 year old engine means it all better be in top shape. Thanks to all for the help.
 
Nice work, sounds like you got it. Good call on the further work, bad connections before and after the power packs can kill them leaving you right back where you started.
 
An older wiser fellow than myself told me the top ten reasons for electrical problems in boats were as follows:
1. bad grounding
2. bad grounding
3. bad grounding
4. bad grounding
5. bad grounding
6. bad grounding
7. bad grounding
8. bad grounding
9. bad grounding
10. something else.
 
To reinforce your solution, I experienced the same symptoms on my '85 Johnson 150 V6. Much of the time the boat would run fine, then, just like a switch, it would drop 3 cylinders. It was VERY much an intermittent problem. The boat always got me home, but always made me worry.

I also repeatedly checked for fuel issues and found nothing. As I go off the coast twice per year, I decided to not **** about, so replaced both Power Packs with new ones, which completely resolved the issue. The most impressive bit was BRP parts availability...I had them overnight, for a then 28 year old engine! nice.

It's an apparently common issue with these old OMC's :
http://www.whalercentral.com/forum/viewthread.php?thread_id=18044&highlight=power+packs&pid=114779#post_114779
 
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Even simpler put....electrical and saltly air/water = eventual problems. Regular maintenance is the cure.
 
I ended up replacing the lot, both CDIs and a pair of coils. Multimeter was telling me that the second, hitherto "good" CDI was not as good as it looked - similar resistance in either direction - not how diodes should operate. I figured if the CDIs were failing then the coils were close behind. Stbd coils were replaced two years ago, along with stator, rectifier and regulator. I think that's the lot now, the entire ignition system has been replaced within 2 years or less. Ran like a turbine all weekend.
 
Just wondering if you used BRP powerpacks or aftermarket CDI powerpacks. I recently had a intermittent miss and put in a CDI unit, it ran even worse. It would start, barely, but as soon as it went into gear it died. Put in a BRP unit, problem solved.... Going to see if CDI will take it back.....
 
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