25 hp power problem

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firefightered

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I have a 90's ? model 25 hp johnson. When in neutral the motor will rev to full throttle and sound good. When I put it in gear at full throttle it acts like i have it at 1/4 throttle. When I try to go to idle it stalls. Any ideas? The motor cover had been painted green before I bought the boat and I am unable to find any model numbers ti identify what I have.
 
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Daviet

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Re: 25 hp power problem

First, don't rev the engine in neutral with no load on it, you might be picking up parts on the lawn.
Look on the transom clamp for a model number, that will tell what year it is.
Start by checking the spark and compression, sounds like you are running on one cylinder.
 
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firefightered

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Re: 25 hp power problem

Thanks for the reply, I only reved it for a second so hopfully no damage. Should I get a spark checker first and see if i have a 7/16" jump?
 
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Daviet

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Re: 25 hp power problem

That's where I would start, if spark is OK check the compression.
 
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firefightered

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Re: 25 hp power problem

I also looked at both coils and they both have a small crack on the outside casing. Is there a way to check the coils to see if they are ok?
 
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Daviet

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Re: 25 hp power problem

You might check your local dealer and see if they have a coil tester and can test them for you.
If coils are cracked, they should be replaced, but might still jump spark to 7'16".
 
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firefightered

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Re: 25 hp power problem

Thank Daviet for the replies. I'll check all this when I get home in the morning. Wish me luck.....
Daviet said:
You might check your local dealer and see if they have a coil tester and can test them for you.
If coils are cracked, they should be replaced, but might still jump spark to 7'16".
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