Poor running, only gotten worse - 1984 15hp

[MichFish86]

Hi everyone,
I have a 1984 Evinrude 15hp outboard that has been in my family for the past 25 years, however it hasn't really been used much until the past two years. I was running it last weekend and it began to sound like it was missing (almost to the point of stalling) anytime that I opened the throttle. If I sped up slowly, it would do fine. I examined the spark plugs and they seemed to be darker with more oil on them than I would expect, so I thought I may have mixed the fuel too rich.

I took it out again tonight after leaning out the fuel and the problem had only gotten worse. It would miss a little at idle, but then would nearly stall at any speed while in forward gear. Eventually it did stall and would not restart until it had cooled off. When it did restart, it ran very rough so I shut it down and oared my way back to the launch. After looking at the plugs this time, the top one looked good, but the bottom had quite a bit of unburnt oil on its electrode and threads.

Any advice or direction you could give me on the issue would be much appreciated.

 

[Daviet]

Re: Poor running, only gotten worse - 1984 15hp

Have you checked the spark and compression?
Is the water pump working properly?

 

[MichFish86]

Re: Poor running, only gotten worse - 1984 15hp

I don't have a compression tester but I can try to borrow one tomorrow and I have not done anything to examine the spark. I forgot to mention I did replace the plugs after the issue started last weekend. Is there a way to check the spark besides pulling the plug out and resting it on the metal while cranking it?

The water pump appears to be working properly with a strong, consistent stream coming out.

 

[fireman57]

Re: Poor running, only gotten worse - 1984 15hp

If it hasn't been used much I would start with giving the carbs a really good cleaning. make sure the jets are clear with a piece of soft wire. After that I would check for spark with a timing light to see if you dropped a cylinder. Coils for this engine are still pretty cheap.

 

[Daviet]

Re: Poor running, only gotten worse - 1984 15hp

You should use an air gap tester to check for proper spark. The spark needs to jump a 7/16" air gap and be bright blue.

 

[Rick.]

Re: Poor running, only gotten worse - 1984 15hp

Good advice above. You should not be guessing at your fuel mix. If your not certain use it in your lawn mower and mix up a new batch of 50/1 TCW3 for your engine. Best of luck. Rick.

 

[MichFish86]

Re: Poor running, only gotten worse - 1984 15hp

Thanks a lot for the advice, guys. I will check the suggested things and update the thread.