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Author Topic:   1987 Evinrude 150-HP Runs Roughly
padrefigure posted 08-24-2015 02:33 PM ET (US)   Profile for padrefigure   Send Email to padrefigure  
Out on the lake yesterday, our 1987 Evinrude 150-HP engine exhibited intermittent power problems. At times, it would struggle to get on plane, and then take off. Several times over the course of the day we would lose partial power, with maximum RPM at about 3,500. Then, it would suddenly take off, quickly climbing to 5,000-RPM. I have heard that intermittent problems are typically electrical, but I am wondering if I might have carburetor problems. The logic being that if one of the three carburetors has a fouling issue, then I could be alternately running on four, then six cylinders. I'm perplexed. What do you guys suggest for possible causes?
jimh posted 08-25-2015 09:28 AM ET (US)     Profile for jimh  Send Email to jimh     
Use an in-line spark tester to check for spark on all cylinders when the engine is operating in the manner that maximum RPM is limited. It is not unusual for OMC engines of that age to have electrical problems in the spark generation circuit called the Power Pack.
padrefigure posted 08-25-2015 10:28 AM ET (US)     Profile for padrefigure  Send Email to padrefigure     
Thank you. I will give it a shot.
george nagy posted 08-25-2015 02:08 PM ET (US)     Profile for george nagy  Send Email to george nagy     
I had a similar issue to yours on my 1987 about 10 years ago and it was the magnets in the flywheel which were very expensive to fix therefore I got rid of it. Mine was a saltwater engine so the rest of the engine was also on borrowed time but you still may not want to spend too much on yours.
dhorton posted 08-25-2015 03:50 PM ET (US)     Profile for dhorton  Send Email to dhorton     
I had the same problem with mine and it turned out to bee a restricted fuel line
padrefigure posted 08-25-2015 07:15 PM ET (US)     Profile for padrefigure  Send Email to padrefigure     
How would I diagnose the flywheel problem? The part is obsolete, but I would guess that a used part would work--what models could I choose from (any 6cyl or only 150HP's)

Thanks for all of the direction.

seahorse posted 08-26-2015 07:53 AM ET (US)     Profile for seahorse    

Look at your flywheel, there were 2 types that year depending your the model number.

The 35 amp charging system flywheel is the one that could have loose or broken magnets inside of it. It has many cooling air vents on the top side where it is possible to look down into the stator.

Most regular 150's of that year have the 9 amp charging system with a flat looking flywheel, there are no air vents in that style. That flywheel uses encapsulated magnets that are never a problem.

tedious posted 08-26-2015 08:56 AM ET (US)     Profile for tedious  Send Email to tedious     
Padre, you don't have enough information yet to be drawing conclusions - this type of intermittent problem is tough to diagnose, and you need to be gathering more information, not proceeding on speculation or guesses.

A spark tester is a great place to start - make sure you have a good strong spark on all cylinders. If you can make the problem happen when you have the tester on there that would be excellent.

When the problem occurred, was there any noticeable difference in the sound of the motor, or the color or volume of the exhaust smoke?


padrefigure posted 08-27-2015 09:15 AM ET (US)     Profile for padrefigure  Send Email to padrefigure     
Other than the noticeable drop in power, no there was no difference in engine sound. I will do the spark test this weekend.
padrefigure posted 09-03-2015 08:45 AM ET (US)     Profile for padrefigure  Send Email to padrefigure     
Hooked up the inline spark tester last weekend and no spark on the starboard bank of cylinders. Ordered replacement power packs (which arrived yesterday) and will install this weekend and report back. Each cylinder also has a coil--how often are these a problem?
tedious posted 09-03-2015 03:40 PM ET (US)     Profile for tedious  Send Email to tedious     
Coils do go bad, but is unlikely that they all failed at the same time. Changing the power pack is a good next step - see how that goes before ordering more parts.

Good luck!

vkr posted 09-03-2015 08:50 PM ET (US)     Profile for vkr  Send Email to vkr     
I had a similar problem with my 1986 Johnson 150. On throttle up it would loose power, but after throttling back and then throttling up it would be fine. Replaced the one power pack and I was back in business. My money is on the power pack. Let us know how you make out with this issue.
Good Luck

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