'64 Johnson 5.5 - Spark Plug Keeps Failing

[Scott in MN]

At least that is what I suspect. Here are the details. I'll put two new spark plugs in the engine and it will run great for ~2 hours. Then, it starts only firing on one cylinder and I lose power. Putting in a new spark plug seems to fix it short term until the same thing happens again.<br /><br />What could be causing this?

 

[Chinewalker]

Re: '64 Johnson 5.5 - Spark Plug Keeps Failing

Hi Scott,<br /> For starters, it's likely not the spark plug...<br /><br /> More than likely you've got a coil or condenser breaking down. Have you had the flywheel off recently? Are the coils cracked or "chalky" looking? Are the condensers the modern "rubber top" type? It's easy enough to localize the problem as you can, one by one, swap parts from one side to the other and note whether the issue follows the part...<br /><br />- Scott

 

[CATransplant]

Re: '64 Johnson 5.5 - Spark Plug Keeps Failing

Right off the bat, it sounds like you may have the wrong plugs in that outboard. What plugs are you using in your 5.5?<br /><br />If it starts right back up after you change plugs, it's probably not the coils or condenser that's causing the problem.<br /><br />So, fill us in on the plugs you're using and how you use the outboard mostly and we'll probably have some advice.

 

[TTravis]

Re: '64 Johnson 5.5 - Spark Plug Keeps Failing

Scott,<br /><br />Take at my 5.5 tune up project on http://outboard-boat-motor-repair.com and read up on the igniton system.

 

[Scott in MN]

Re: '64 Johnson 5.5 - Spark Plug Keeps Failing

Follow up time.

Beautiful evening here in St. Paul, MN. Couple of neighborhood friends and I reopened this issue with a couple of homebrews and the Twins game on the radio (damn it, they lost to the weak Tigers). Anyways, turned out it was one shorted out set of points that was causing one cylinder to fire very intermittently. Salvaged an old set of points off an old Evinrude and it started working great.

I treated everyone to another round after our success!

 

[bktheking]

Re: '64 Johnson 5.5 - Spark Plug Keeps Failing

This post was over 5 years ago, you just fixed it yesterday or 5 years ago?????

 

[Scott in MN]

Re: '64 Johnson 5.5 - Spark Plug Keeps Failing

Fixed it yesterday!

 

[samo_ott]

Re: '64 Johnson 5.5 - Spark Plug Keeps Failing

The last year of the 5.5 ever made... sigh...