1990 25HP Johnson cuts off violently

bapowell

Recruit
Joined
Jun 29, 2005
Messages
3
I have a 25HP 1990 Johnson Outboard motor with an electric starter that has worked well for many years until now. It will cold crank and start just like it always has, but after 5 to 10 minutes of running wide open it will begin to sputter until it shuts down with a rather violent jerk. At this time it will not restart. I have found that if I tilt the motor up and out of the water and let it sit for 5 to 10 minutes, I can lower it and start it. It will again run for 5 to 10 minutes and shut down. When the motor is lifted, I have noticed a small amount of un-burnt oil dripping from within the carborator intake of this 2-cycle engine. It seems like the engine is flooding only after running wide open for 5 or so minutes. This engine has always had trouble idling. What's going on?
 

fireman57

Captain
Joined
Aug 24, 2004
Messages
3,811
Re: 1990 25HP Johnson cuts off violently

Welcome to iboats. Sounds like you are overheating. Get some temp sticks from your dealer or try to hold your hand on the head for a slow three count.
 

bapowell

Recruit
Joined
Jun 29, 2005
Messages
3
Re: 1990 25HP Johnson cuts off violently

I've checked my gas/oil mixture and the water pump appears to working well. What else could cause over-heating?
 

CATransplant

Admiral
Joined
Feb 26, 2005
Messages
6,319
Re: 1990 25HP Johnson cuts off violently

Plugged water lines, blown head gasket, crud in the water jacket around the cylinders.<br /><br />Bottom line is this: If your outboard is slowing down and stalling after a while of running...it's very likely overheating. You can pull it out and fix it, or you can destroy your engine by continuing to use it.<br /><br />The draining fuel when you tilt the motor isn't that significant. The sputtering and stopping after running is.
 

bapowell

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Joined
Jun 29, 2005
Messages
3
Re: 1990 25HP Johnson cuts off violently

I'll check out your suggestions. Thank you very much for your insights.
 
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