1965 Johnson 3HP sputtering.

Todd N

Recruit
Joined
Aug 17, 2003
Messages
5
I have a 1965 Johnson 3HP Model JH 20B that I inherited from my dad. The motor has great spark and it starts on the first or 2nd pull. It will run roughly but only on full choke. Every time I take the choke off, the engine sputters and dies out. Any ideas?
 

Paul Moir

Admiral
Joined
Nov 5, 2002
Messages
6,847
Re: 1965 Johnson 3HP sputtering.

Three things come to mind. <br />Zeroth: Make sure your high (if applicable) and low speed carburator mixture adjustments are set right. Joe Reeves explains how here.<br />First, if the ignition coils are cracked from age, then they arc over as you pick up revs, and the engine dies. It's a fairly common problem: I had a 3hp do the exact same thing. You may be able to inspect them without removing the flywheel - I'm not sure if your model has inspection holes in the flywheel.<br />Second, if it runs for a little bit or idles, you may have a fuel flow problem. Probably it's got a clogged fuel filter, which is above the brass nut on the fuel tank.<br />Third, your carburator probably need cleaning. Strip it, soak it in carb cleaner, blow it dry and rebuild. This is most likely your problem by what you described.<br /><br />Here's an article you'll probably find interesting.<br />You'll need a manual to read over for 1 and 3. You can order one from Iboats, or you can probably borrow one from your local library.<br />Good luck!
 
D

DJ

Guest
Re: 1965 Johnson 3HP sputtering.

Todd,<br /><br />Agree with paul on the coils and carb. A carb. rebuild is probably in order.<br /><br />While in the carb, replace the float if it's the original cork style.
 
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