Mercury 150 XR6 - cutting out

[Ssveeggen]

First post on here. Looks like a great place for information.

Serial#0T588256
year -2002
Engine started running rough late last season. I have troubleshot it to the point of finding that the issue is in the control module. When on the water I removed the connector that controls the neutral safety switch, low oils sensor/ and high temp switch. This immediately cleans up the issue. I purchased a different control module and replaced it. Hit the water and it ran perfect, so I thought I fixed the issue. After running it for 5 minutes or so we stopped and let the kids swim for about 20 minutes. Fired it back up and immediately had the same result as before. So I unplugged that connector and it cleansed up again.
At home I tested the neutral safety switch, high temp switch and sensor and low oil sensor, they all worked properly. Reached all grounds and made sure warning beeper was working also.
Any ideas? At a loss on this right now and I don’t want to run it without those sensors hooked up.
Also I took it to a mercury dealer to work on it and they refused because they could not make out the serial number on the boat. This is a newer motor on an old boat and they stated they cannot work on it. So taking it to a dealer is out of the question.
Thanks!

[Ssveeggen]

Anyone have any ideas?

[lpugh]

Find a Mercury dealer that will work on it. At the very least you will need a factory service Manuel and spend some getting familiar with this motor if you are mechanically inclined.
Unless you are referring to the ECM there is no module for those sensors
Neutral safety switch is in the throttle/shift control unit not on the motor. There is a shift interrupt switch on the motor though

Would be helpful to explain in detail what you mean by running rough

[Ssveeggen]

I have the factory manual. Thats how I know what that plug off of the control module with 4 wires control the Temp switch, low oil switch and shift switch. The engine runs fine at full throttle. Everywhere else including idle, it sounds like it’s down a cylinder. Unplugging that Harness mentioned above, cleans it up completely. I am mechanically Inclined and have tested all switches and grounding.
Alos as I mentioned. I have taken it to a mercury dealer, 3 to be exact. They will not work on it because they cannot makeout the tag on the boat. Claim it’s an insurance issue of liability if they work on it.

[lpugh]

I am following you now as the ecm is called a control module on that motor, I suspect you have a intermittent problem with the shift interrupt switch. Check to see if it is normally closed or normally open, Either disconnect it or jumper it to duplicate a in gear position for testing purposes. If that switch sends a in neutral signal to the module it will attempt reduce rpm and probably drop 3 cylinders

This makes the most sense to me
Hope this works out for you
Let us know