9.5 Johnson runs very rough after lower unit seals replaced

[brmurph]

We have had this 9.5 horse Johnson in the family since new (1964 model) and every year it starts right up and runs great until now. Last year I decided to spend a little money on it and get the lower unit seals replaced, I really thought it would not be a big deal but the shop that did it seemed to have some trouble and suggested I get something newer. That being said as far as I knew all was fine but when I went to start it it would no longer idle, no power and ran very rough, so rough I was afraid to run it long. I don't feel I can go back to the shop (I won't go into the details) but I would like to get this fixed. My question is would it be possible to mess up the lower unit (maybe the exhaust) to the point that the motor will no longer run right?

I have checked the compression and it is fine (both 70 psi which I understand is fine for this motor), spark (new plugs) looks great, fresh gas with new tank and fuel line. It starts right up and even seems to run well for about 5-10 seconds then runs really rough. It might be my imagination but it seemed to start running bad about the same time the thermostat opened and water started pumping. Oh and I always run the motor with the top off as it has the common exhaust leak that runs better this way.

Any thoughts? Thanks in advanced.

 

[Rick.]

Re: 9.5 Johnson runs very rough after lower unit seals replaced

Does the prop spin freely in neutral? It could be that your carb. slow speed needle is not set right or leaking spark. It could even be your carb. needs a cleaning and kit. Fire it up at night and look for errant spark going to ground. Do an air gap spark test. You should be able to hold your hand on top of the head for a slow three count when it's up to temp. Check it out a bit and let us know. Best of luck. Rick.

 

[brmurph]

Re: 9.5 Johnson runs very rough after lower unit seals replaced

I do agree it could be a carb or electrical issue (in fact at first that is what I thought) but before I mess anything else up I kind of wanted to rule out the lower unit as an issue. Seems like such a coincidence that we have never had trouble in almost 50 years until the preventative lower unit maintenance was completed.

I did do spark plug air gap check and looks really good, prop spins fine in neutral. Will check for spark leakage at night this weekend.

Could lower unit cause it to run bad or should I rule that out? My first thought is lower unit couldn't cause this but now I wonder.

Thanks.

 

[Monte1961]

Re: 9.5 Johnson runs very rough after lower unit seals replaced

well unless there is no oil and or someone actually tore in to lower unit, my guess is no if only routine maintenance was done. Do what the earlier posts suggests. I am thinking either wires and or carb. Post back your results.

 

[Rick.]

Re: 9.5 Johnson runs very rough after lower unit seals replaced

My experience says no but my experience also says anything is possible. LOL. I would remove the plugs and then spin the flywheel clockwise while it's in gear just to see it there is any kind of a resistance to rotate. If that proves fine then you can rule that possibility out IMO. http://forums.iboats.com/showthread.php?t=299680 Have a look through the top secret file and see what pertains to your concern. Post questions as necessary. Rick.

 

[brmurph]

Re: 9.5 Johnson runs very rough after lower unit seals replaced

Just wanted to post the resolution of this. Turned out it was the carburator, I put in a rebuild kit which was basically just a float (pretty sure this was the problem), needle and seat. The carb was pretty clean so I did not bother to pull out the well plugs. This was a really easy job.

Thanks for the advise to stay away from the lower unit (I was so sure ..