2005 Johnson 90HP low RPM miss

[Birdman84]

I have been trying to trace down a low RPM miss on my 2 stroke Johnson 90 and still unable to figure out the cause. It misses at idle speed up to about 1600 RPM's then smooths out. It occasionally will die out in put into gear at idle speed. Here is what I have done so far in the past 3 months:

Replaced optical sensor, coil packs and power pack - all new OEM (had a no spark problem)
Carbs rebuilt by mechanic
Replaced spark plugs, plug wires, water/fuel separator, fuel filter
Checked fuel pump diaphragm, unable to see any signs of fuel delivery problems
Replaced key switch assembly - OEM (another no spark issue)
Replaced stator - used OEM (mine looked pretty bad. The used one I bought appeared to be in good condition)

Right before replacing the stator it started giving me misfiring at all speeds, so this issue has progressively gotten worse as time has gone on and I continue to run it. After replacing the stator it is now back to just a low RPM miss but I am concerned that whatever the problem is, may be causing damage to the stator or other electrical components. It seems odd to me that I have had recent issues with so many electrical ignition components.

I have performed DVA and resistance checks on the ignition components but all readings have been good (this is in a barrel at home). If I pull one of the 2 plugs on the right (looking from behind the motor) the RPM's do not change. If I pull one of the two on the left side, the motor sputters and almost dies out.

Any suggestive advice on what to check next would be greatly appreciative.

 

[racerone]

When you pull plug wires off one at a time the motor should drop in RPM.------Something is wrong on the right side.------Orange/blue stripe wire is on the # 1 coil ?

 

[oldboat1]

Cannot test on muffs, as you probably know (runs lean, yielding a "lean sneeze" that can sound like a miss.)

 

[Birdman84]

Yes, orange/ blue stripe is on top, orange/ green on bottom. Grounds from power pack are secured behind coil packs against the metal tabs.

I don't run it on muffs, I have a 60 gal barrel I dunk it in. Pisses of the neighbors less. I get the relatively same behavior whether in the barrel or boat in the water. Little worse in the water with full back pressure.

Yesterday I disconnected the rectifier from the stator and ran the motor with no change. Thought maybe the rectifier could be going bad but no issues with tach or charging

 

[Birdman84]

Also I verified with a spark tester that I am getting spark on both right cylinders, consistent with the left side

 

[racerone]

What are the results of a compression test ?------When you pull plug wires on the one side the motor MUST drop in RPM.----Concentrate on cylinders 1 and 3 .----I say there is something wrong there !

 

[Birdman84]

Thanks racerone, so #'s 1 and 3 are on the right? Compression test was great, all between 102-104 psi. I've looked into the readings and it seems most are between 90-110 or so. Deviation between the 4 is very slight.

 

[racerone]

The top cylinder on the block is usually #1.

 

[deedah37]

I have a 2000 90HP OIS version and having similar issues IE Running rough....Please let me know if you resolved the issue and how?