1975 johnson 25hp out board runs rough in neutral

fishfreak79

Recruit
Joined
Mar 26, 2011
Messages
1
Im trying. To get an old boat I got from my uncle to run good enough so I don't need to be scared to go out. I put the motor I a 55 gal drum and ran it for about 15 min and it runs good in gear but in neutral it runs and then putts and back fires kind of I ordered water pump kit should the carb be rebuilt also or could this be lgnition issues? ??
 

Cofe

Lieutenant Commander
Joined
Apr 23, 2009
Messages
1,883
Re: 1975 johnson 25hp out board runs rough in neutral

Putt and backfire in neutral can be several things. Most common is a dirty carb. I would remove, clean, and rekit the carb first.
 

imokintex

Cadet
Joined
Oct 14, 2010
Messages
20
Re: 1975 johnson 25hp out board runs rough in neutral

If all else fails and as a last resort..........I had a similar problem a long time ago and found out that the key that aligns the flywheel was partially sheared and threw the motor out of time. Drove me crazy untill a friend told me about it and I pulled the flywheel.
 

kbait

Commander
Joined
Nov 13, 2007
Messages
2,446
Re: 1975 johnson 25hp out board runs rough in neutral

Clean and reset your points when you have the flywheel off. Check the spark with a tester, as just holding the plug to ground will show spark but not quality under compression. You need 1/4" bright blue bolt in open air to be good. Good luck!
 
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