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.
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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.
Look into throat of carb, open throttle up and make sure butterfly is opening all the way. Could be not getting full throttle.
have had three mechanics work on it ,still has same problem.
Fuel line partially clogged?
Power pack? Had a merc do that once and that was the problem.
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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.
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.
it doesn't slow down but sounds different like its missing and won't go any faster.
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.
could a short in the wiring from stator cause this?
Fuel pump...while on water with motor cowl off and airbox removed, duplicate the problem. Once it starts to act up spray carb throat with a little gas. If if speeds up and takes off replace pump and you are done. May need two people to do it safely.
Also if you can pull plug wires one by one while it's acting up and see if any do not make a difference, that will tell you if it's a fire/ cylinder issue. Highly doubtful but possible. Use insulated pliers unless u like being bit by the spark.
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Meant to add....put gas in a spray bottle to spray gas when it's messing up. I have diagnosed a many this way. You can also do it with muffs on the motor but sometimes you can't get it to act up unless it is under a load.
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Hey Ichabod,
I really like all the suggestions the crew has already given you. OMC fuel lines are famous for having the fuel line O-ring leak air and cause problems...Just an idea...Good Luck
Check the fuel pick-up inside of gas tank. Mine did that and it was cracked ABOVE the fuel level in tank.
One question. I find a lot of people that are using a 6 gallon tank they close off the tanks air by tighting the cap down so that the gas gets vapor locked and will not run correctly. I seen a man and his boy having this problem this past summer and like to have never got him to loosen the cap. Well when he finely gave up and did loosen the cap the motor did just fine. This could be your problem if the motor is running for the mechanics and would not run for you. Some times it is the simple things that get over looked.:twocents
:Doh: Did not notice this was a 2 month old post. I would like to know if this problem was solved and what was the problem and fix. It could helpmeandmany other fellow boater's in the future. Thanks in advance and sure hope you have fixed the problem.
Go simple first - Bad gas? No way to know so get fresh 100% 89.9 or better. Use the old in lawn mower or pour it out and discard. Mine did exact same thine and bad gas was the culprit! Good luck.
i had this issue on a 92 model evinrude it was the primer lever was sucking air i replaced the diaphragm and the red plunger thing
sounds like you had three people . lol you got my luckQuote:
Originally Posted by ichabod
What all did they do ? If a fuel pump hasnt been rebuilt thats where i would begin.
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Watching U-Tube the fuel pump could get a hole in the Diaphragm that will cause the motor to not run faster than half speed