50 hp No Power

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SeanWilliams

Recruit
Joined
Jun 18, 2007
Messages
2
I have a '71 Evinrude 50hp(50173S). When put in gear and under load it has no power. It seems to idle fine, and when in neutral it seems to rev to normal rpm range. It was locked up at one time, but have had the upper and lower crankcase seals replaced and had the pistons and cylinders inspected, all fine. I have also replaced the coils and other electronics. Any suggestions on what else may be causing this issue?
 
fireman57

fireman57

Captain
Joined
Aug 24, 2004
Messages
3,811
Re: 50 hp No Power

Even though you said you have replaced the coils do a spark check and make sure that you haven't dropped a cylinder. Make sure the spark is bright blue and really jumps. You may have another coil that has gone south or is not making a good connection. Remove all wires and clean the connections well.
 
Silvertip

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: 50 hp No Power

Have you checked compression and spark on each cylinder. Have you pulled the spark plugs to see what they look like? A two stroke will sound pretty normal idling with one dead cylinder. My guess is ignition on one cylinder is dead or a carb is plugged up. Start the engine and while idling, pull one spark plug wire. The engine might die or as a minimum, it should drop rpm or at least sound different. Reinstall the wire and try the next one. If there is no change, you found the dead cylinder. The next thing you need to do is determine if its fuel delivery to that cylinder (dirty carb), spark, or a mechanical condition (blown head gasket, hole in piston, etc.).
 
S

SeanWilliams

Recruit
Joined
Jun 18, 2007
Messages
2
Re: 50 hp No Power

I have checked the compression and spark on both and are good. When pulling apart the carbs, they were pretty cruddy. And one of the floats was missing the retainer spring. I am going to get a rebuild kit and go from there. One other note.....When I originally tested, it ran great for about 100 yds, the went to the bogging down. Now it boggs down from the get go. Thanks for your advice.
 
fireman57

fireman57

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Joined
Aug 24, 2004
Messages
3,811
Re: 50 hp No Power

Sorry in my first post I forgot: Welcome to iboats. Yes, a good carb cleaning and rebuild should solve your problem. Take your time so you don't have to do it twice.
 
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