Johnson 25 hp fouling plugs and sneezing

[Chevdog]

I have a Johnson 25hp outboard. I recently put a 30hp intake and carb on it. I have read of quite a few guys doing this with great success. Ever since I changed the intake and carb over, the boat runs horrible, though it has always smoked quite a bit. I have rebuilt the carb, and am running my fuel at 50:1. The only way that I can get my motor to run anywhere near decent is to advance the hell out of the timing before the butterfly starts to open. If I try to do a link and sync, it will start to produce what I believe is a lean cough, almost a kickback of some sort and throw out a plume of smoke. I also replaced my plugs twice, and are now wet with fuel. I don't know where to start as I have symptoms of running to rich, but also to lean. The compression on both cylenders are roughly 120, very close to eachother. I have tried testing the electrical system, but don't have a peak voltage meter. Does this sound as though it could be a lower crankcase seal? Also both cylenders look to be running about the same from the way the spark plugs look. Any help would be appreciated, I would love to get my boat running again and get back out there fishing,
Thanks, josh.

 

[Will Bark]

Re: Johnson 25 hp fouling plugs and sneezing

Have you checked the flywheel key to see if it damaged and is out of time?

 

[EddiePetty]

Re: Johnson 25 hp fouling plugs and sneezing

Are you running this engine waterborne or in a barrel?

 

[jasper60103]

Re: Johnson 25 hp fouling plugs and sneezing

What model number or year is this motor?

 

[Chevdog]

Re: Johnson 25 hp fouling plugs and sneezing

The model number is j25telets. It is a 1992 Johnson 25hp tiller electric long shaft. It is mounted to a 14' Klamath. All of the running has been done inside of a drum so I have back pressure on the exhaust. I have taken it out one time to run it, and it just doesn't seem like the power is there. I would have thought with the new carb and intake it would have been a lot more noticeable. This was with the timing extremely advanced. Like I said, if I do a link and sync, it constantly hazes, and will sneeze if I slow the idle down. If you guys need anymore info for troubleshooting, please ask, I am very tired of having a boat that I can't use,
Thanks.

 

[EddiePetty]

Re: Johnson 25 hp fouling plugs and sneezing

Just to humor me, when you run the 25 in a barrel, set a fan in front of the engine to keep exhaust away from the intake. Next measure the spark strength with a spark tester, or, pull the plug leads one at a time to verify that each cylinder is firing.
Failing these steps I would reinstall the original components to see if the condition follows.

 

[bobbarone56]

Re: Johnson 25 hp fouling plugs and sneezing

Did it run good before you changed the carb?? if so reinstall the old carb and see if it goes back to running normally

 

[Whoopbass]

Re: Johnson 25 hp fouling plugs and sneezing

You might want to go through the carb again and make sure its clean. My 25hp Evinrude was doing that crap and I couldn't figure it out so I installed a 30hp carb from a donor motor I had and all the coughing went away. Now it purrs instead of chugging at low speeds.

 

[Chevdog]

Re: Johnson 25 hp fouling plugs and sneezing

I think that I will just go through the carb again. I've done it twice but have not pulled the welch plugs yet. If I pull the plug wires while running it misses about the same on both cylenders. Like I said before, the plugs both look the same as though both cylenders are running similarly crappy. Not just one cylender. I have also tried running the origanole 25hp carb and it runs just as bad. I may take the intake off and put the origanole back on. But as far as it running before, it has always smoked, but not nearly as bad as it does now. I have sprayed brake clean around everything and have not found any vacum leaks.I will go through the carb again and get back to report the results.

 

[Whoopbass]

Re: Johnson 25 hp fouling plugs and sneezing

Do you have a manual primer injector for cold starts instead of a choke? If so pull it out and hold it out while the motor is running and see if that helps. My outboard is running like crap again and when I pull out my primer injector it runs fine. I haven't had time to figure out why that works but it does.