# 9.9 johnson bogs down



## tnant1 (Nov 21, 2006)

I have a 95 johnson 9.9 that I rebuilt the carb last winter and it still does the same thing. When not at full throttle it runs fine but at full throttle it sometimes goes ok but most times it Boggs down. Ideas? I am thinking fuel pump now.


Outdoor Hub mobile, the outdoor information engine


----------



## Drew318 (Mar 25, 2010)

I had a similar problem with my 48 evinrude. It ended up being a cracked spark splug. Just thought I would throw that out there. Good luck there are some very knowledgeable guys on here


----------



## dwmikemx (Mar 22, 2008)

I would inspect your fuel line and squeeze bulb first. The ethanol in the gas now a days plays havoc with fuel lines.


----------



## turkeyt (Apr 13, 2006)

My 94 was the power pack breaking down. Motor would run fine until it warmed up and then would fire only on bottom cylinder. It will run fine on one cylinder, but at only half the power. Yours could be cutting in and out. You need to determine if your problem is fuel or electrical related. The power pack puts out alot of juice and takes special gauge to check. I just pulled the top wire from power pack to coil and flipped it with the bottom and checked each plug for fire. The fire just jumped from top to bottom when i flipped them. If you could get your motor to act up on muffs you may be able to check it. If it acts up you can check the spark from the plugs to make sure you have fire all the time.

When you put the kit in your carb did you soak the carb and make sure those little holes and jets are real clean? Those carbs can get gunk in the smallest places. Does your primer bulb stay pumped up when your motor is running? Just a few things to check??


----------



## johnrude (Mar 29, 2009)

any chance you can run the motor in a garbage can full of water ? this only to try something before pulling the carb off again and putting any serious money into it. i would get a can of seafoam and pour the whole can into your gas tank and run the motor in the can. and then check your squeeze ball to see if that is an issue and also to see if it may be you have a fuel pump problem. and if you can run it for awhile the seafoam may get the job done too ! also put in a new set of spark plugs first. just my 2 cents worth !


----------



## ezbite (May 25, 2006)

is your vent open on the fuel tank? just askin


----------



## RushCreekAngler (Jan 19, 2011)

turkeyt said:


> When you put the kit in your carb did you soak the carb and make sure those little holes and jets are real clean? Those carbs can get gunk in the smallest places. Does your primer bulb stay pumped up when your motor is running? Just a few things to check??


++ on that - My 73 Merc 7.5 had not been used in 7 years - I had to pull the carb 4 times, and used almost a full can of carb cleaner before I got all of the crud out. Some of the ports are not much larger than 4lb mono - 

A Merc mechanic told me that many times on a really gunked up carb, it may take a few of cleanings to get it back to normal.


----------



## tnant1 (Nov 21, 2006)

Thanks for all the comments. I have replaced the plugs and made sure the vent was open. I usually put some seafoam in every tank but I like the idea of putting in a whole can. Might give that a try. As far as the soak, I soaked it for at least 24 hours which might not have been enough. Might just try to run the heck out of it with a full can of seafoam just for grins. The lines have been replaced but cannot remember if I changed the bulb or not. It does stay tight when it is running.


Outdoor Hub mobile, the outdoor information engine


----------



## UFM82 (Apr 6, 2004)

So we can probably eliminate those things. When you say "bogs down" I'll assume you mean it loses power. A couple of things are happening at WOT.
1) Fuel flow is at its highest. If your fuel pump is weak or failing it could be starving the engine at high rpm. If it's not pumping enough fuel to keep the bowl filled it will lean out and the engine could stumble. You can diagnose this somewhat when you go out again. Peg the throttle and when the engine starts stumbling, pump the bulb or have someone else pump it for you. If it is a fuel pump issue squeezing the bulb will act as the fuel pump and the engine should run fine. If not, it's not the pump itself. 
2) Timing is advanced fully. You may want to have it checked and do a sync. 
3) The fuel/air mixture is as dense as it's going to get and it needs all the spark possible to ignite it- see the power pack comment above. 
4) It's using as much air as it ever will- make sure the proper cover vents are clear so the engine can ingest all the air it's supposed to. It's not common at all but I've seen two engines that didn't run properly because the cover slots were plugged with spiderwebs and stuff. (They were both in Canada and yes, it can happen.) 

Eliminate each step and you'll find the issue.


----------



## captk (Mar 13, 2008)

Thumbs on those suggestions, take the cover off and try it


----------



## tnant1 (Nov 21, 2006)

UFM82 said:


> ...
> 4) It's using as much air as it ever will- make sure the proper cover vents are clear so the engine can ingest all the air it's supposed to. It's not common at all but I've seen two engines that didn't run properly because the cover slots were plugged with spiderwebs and stuff. (They were both in Canada and yes, it can happen.)
> 
> Eliminate each step and you'll find the issue.



It's odd that you say that. This motor has a "cowl" (for lack of a better word) that basically only keeps the throttle cable from hitting the flywheel. When I removed that it seemed to run perfect. There is nothing in the "cowl" but for some strange reason it ran better without it. Very odd.


----------



## UFM82 (Apr 6, 2004)

But there has to be a passageway or path for air to get into the engine compartment. The carb is right in front and does not use a filter apart from maybe a chamber of some sort. If the entire engine shroud (lower and upper) were completely sealed the engine could not draw air in and it wouldn't be able to run. Make sure there are no restrictions anywhere blocking airflow. Since you said it ran fine without the cover I'm thinking you've found the issue. I'd like to see a picture if that is possible. Is the "cowl" under the cover or is are you referring to the cover itself? You've confused me a bit with that comment. 
I'll take a peek at the 9.9 I have at the house to see what I can find as far as an air path. I'll post tonight on what I find.


----------



## miknad10 (Jun 12, 2011)

had same problem with my 96 was fuel pump


----------



## turkeyt (Apr 13, 2006)

UFM82 said:


> But there has to be a passageway or path for air to get into the engine compartment. The carb is right in front and does not use a filter apart from maybe a chamber of some sort. If the entire engine shroud (lower and upper) were completely sealed the engine could not draw air in and it wouldn't be able to run. Make sure there are no restrictions anywhere blocking airflow. Since you said it ran fine without the cover I'm thinking you've found the issue. I'd like to see a picture if that is possible. Is the "cowl" under the cover or is are you referring to the cover itself? You've confused me a bit with that comment.
> I'll take a peek at the 9.9 I have at the house to see what I can find as far as an air path. I'll post tonight on what I find.


Is he is talking about the air silencer that fits on the front the carb? That part has no filter but there could be something living in there and that would cause a blockage of air. The air has to go through the motor cover and then through the silencer to get to the carb. Just a thought


----------



## tnant1 (Nov 21, 2006)

By 'cowl' I meant the plastic air redirect under the cover. Not the cover itself.


Outdoor Hub mobile, the outdoor information engine


----------

