In need of help on Mercury SportJet 120 XR2! Cylinders 1 and 3 not running!

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Hi there,

I have a 99 sugar sand mirage with a SportJet 120 in it. I have had the boat for several years now and have never had a problem until today. I was using the boat earlier today for fishing, and when I was approaching the dock at the end of the day I felt that the engine was running differently. Once at the dock, the engine turned off on its own and from then on it was difficult to start up again. I took it out of the water, cleaned out the carbs and put the boat back in the water to test it out. It had difficulty starting and when it did start I could hear that it was only running on 2 out of the 4 cylinders. Here is what I know:

My problem: cylinders 1 and 3 are not working. (I know this because when it is running, the engine only shuts off when I pull the spark plug cap off cylinders 2 and 4)
-I tested all 4 cylinders and all of them have equal pressure of 150psi
-I replaced all 4 spark plugs
-I tested all 4 spark plugs and they all have a strong spark
-When I took out the spark plugs for inspection, none of them were dry (meaning that gas is getting to them ok)
-I cleaned out the carbs and everything is fine with them

Is it possible that the spark timing is off? Could this be an electrical issue?
Any help/advise/response is greatly appreciated! Thank you in advance for your help!

 

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Re: In need of help on Mercury SportJet 120 XR2! Cylinders 1 and 3 not running!

In addition, I have the RED stator and all magnets on the flywheel are in their correct positions.

 

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Re: In need of help on Mercury SportJet 120 XR2! Cylinders 1 and 3 not running!

An update:

I swapped the CDM modules and I still have the same problem. Only cylinders 1 and 3 are not running. I moved the plug wires as well, and no change. All four cylinders have a VERY strong spark.

I did an ohm test on the trigger last week and I was getting very low numbers so I ordered a new trigger. It came in today and I replaced it and I still have the same problem of cylinders 1 and 3 not running.

I did an ohm test on my RED stator and I get a reading of 680 (from what I found on the internet, 500 - 700 should be OK)

I also put in new spark plugs and injected some extra fuel into cylinders 1 & 3 and started it up. Still no change.

 

[kend301]

Re: In need of help on Mercury SportJet 120 XR2! Cylinders 1 and 3 not running!

Check reid valves and fuel recirculation system .