2000 Johnson 90hp with Optical Ignition System

I noticed a change in the way my motor sounds. I have only owned it a few months but I'm almost sure it is quieter when I run it while out of the water. It seens to run normal when on the water but is idling rougher than I remember it being a week or two ago. I noticed that the port side cylinders are not firing. I discovered this by pulling the plug wire while at idle. No change in RPMs or sound. If I pull either of the starboard side plug wire the engine stumbles and dies immediatly Ok, I pulled the plugs out and put them in the plug wires. I cranked it up and no spark on the plugs and no gas coming out of the hole in the cylinder either? When out of the water the motor is slow to build RPMs. If I open the throttle wide open, it takes 3-4 seconds for the rpms to get to 5500. So, I put it all back together and went to the water. I put it in the water and as ussual it ran rough at idle. When I push the throttle to wide open, the RPMs come up slowly for about a half a second and then "BAM!" IT takes off like a rocket and runs like nothing is wrong! I never noticed this before but it could have been this way all along, although I'm sure it was louder out of the water in the past. Is it possible that it sinces the torque load and turns the two cylinders on and then back off when not needed? It is an Optical Ignition System. Does this make a difference?

Re: 2000 Johnson 90hp with Optical Ignition System

That motor should run on all 4 cylinders all the time. Do not rev it up out of the water, as it can cause serious damage to the motor.

I recommend you get a OEM service manual and troubleshoot the motor's ign system. The SLOW system will kill spark to one bank of cylinders, so that is a good place to start.

Re: 2000 Johnson 90hp with Optical Ignition System

Chris 1956, I assumed that it should run on all 4 all the time but when I had neither any spark nor fuel to the cylinder, it made me question the situation. Shouldn't there be some gas being blown out of the sparkplug hole when the engine is running and shouldn't I be able to see the sparkplug "sparking" at the same time?

Re: 2000 Johnson 90hp with Optical Ignition System

You may or may not see gas blowing out the spark plug hole. However, you will see a spark every time. Fix the spark issue first, and they see if you also have a fuel issue.