johnson 9.9 runs better with 1 plug ou

Does anybody know why a 2 cylinder 2 stroke would run better with one plug removed

Re: johnson 9.9 runs better with 1 plug ou

Sounds like one cylinder is not firing correctly to me. I would check spark and compression to start. I'm sure some of the experts will chime in and help you out a lot more then I can.

Re: johnson 9.9 runs better with 1 plug ou

Do you mean one spark plug out of the block or one plug wire off ??

Re: johnson 9.9 runs better with 1 plug ou

One plug completely removed. I can get it to run with both plugs in but I need tokeep the revs high

Re: johnson 9.9 runs better with 1 plug ou

I've cleaned the carg 4 times, changes the dual coil. The motor was submersed but has run for an hour but died after 20 minutes. then I cleaned the card again and replaced the coil. the old coil had 2 different ohm readings

Re: johnson 9.9 runs better with 1 plug ou

Sounds to me you have lost the operation of the cylinder that you have removed the plug from. If that cylinder is not firing, the motor will run a little better if you remove that spark plug because the other cylinder will not need to overcome the bad cylinder's compression.

That being said, you need both cylinders so I would do a proper spark test. You didn't give the year of the motor so I don't know whether you have points & condensers or a powerpack. Points will corrode quickly after being submersed and that could be your problem or it could be many other things.

Gives us the year and anything more on the symtoms and we should be able to lead you in the right direction.

Re: johnson 9.9 runs better with 1 plug ou

You don't mention the year/model number, this may make a difference in the electronics.

Google "leeroys ramblings" One of the articles there in the outboard repair section is in depth about recovering a submerged motor & getting it running. This may give you some insight. You may have water in the rubber boot connector to the coils near the head.

Re: johnson 9.9 runs better with 1 plug ou

What's the compression on it?? A model # would help.

Re: johnson 9.9 runs better with 1 plug ou

Good morning,

This is a Johnson 9.9 1993 CDI & dual Coil. I have a spark on the lower cylinder - not sure if its strong enough and I have compression because its blowing stron when running with the plug out.

Re: johnson 9.9 runs better with 1 plug ou

Just because it's blowing strong when you have the plug out doesn't mean you have good compression. If you've replaced the coil then maybe your power pack is the issue. From what I have heard though just because you can see spark when the plug is grounded to the block doesn't mean you are getting a strong enough spark. You need an "air gap" spark tester to really determine that.