25 hp johnson half speed

[ichabod]

1999 Johnson 25 hp starts and runs find to half speed but bogs down when you try to go faster . carb,has been rebuilt ,power pack changed compression good.

[Cray]

Look into throat of carb, open throttle up and make sure butterfly is opening all the way. Could be not getting full throttle.

[ichabod]

have had three mechanics work on it ,still has same problem.

[EWS]

Fuel line partially clogged?

[Big Smooth]

Power pack? Had a merc do that once and that was the problem.


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[doggone]

Could be a small air leak in the line somewhere or for some reason the fuel pump is not keeping up. Not saying for sure....but I have seen this multiple times when it was one of those two things. As long as you run slow enough the fuel bowl will stay full. When you shower down the fuel bowl runs down and motor starves. You slow down and fuel bowl fills back up. I just had a 9.9 2004 Johnson just do that and it had a little leak in the fuel line between the pump and bowl.

[Cray]

Lets try this. When you say it Boggs down, are you saying it runs same rpm and won't run any faster or are you saying it actually starts to slow down when you go full throttle? If it is dying down, it's either flooding or loosing spark. Let's assume it's not flooding since you didn't say anything about smelling or seeing excess gas. That leaves us at spark. With new power pack we will assume that's good. Now we are at the stator. It should have a timing advance tied to throttle. This could be out of whack, stator could be loose or bad, flywheel key could be bent or sheared causing it to be out of time. Any one of these or a combination would cause it to fall off as you advance throttle.

[ichabod]

it doesn't slow down but sounds different like its missing and won't go any faster.

[Cray]

Here is something you can try. Get it on the water close to ramp. When it's safe run it like that for a few minutes and cut motor off while it's running like that, don't cut throttle. Make sure you have your life jacket on and be ready for it to pitch one way or another. Then use troller to get to trailer and load. You want to pull plugs and see if one of them is wet. That would tell you whether you have a coil or pack is bad.

[ichabod]

could a short in the wiring from stator cause this?