Hi. My name is Tom. I have a 396MY with Merc 8.1 gas engines. I have been dealing with an issue of stalling out on the starboard engine. I will give you the details. The engines starboard and port, after having be warmed up, once under load and approximately 1/2 hour to an hour underway, the starboard engine stalls out.
After cooling down for approximately 20 to 30 minutes, the engine will be able to be restarted. This has happened on multiple occasions. The boat cannot be trusted.

I have had the manifolds changed, the risers changed, all belts replaced, oil changed, etc, etc. It seems to be electrical, but we can’t understand what it is. Further, we had the computer control module from the starboard engine switched to the starboard side. The same problem happened again on the starboard engine.
We had the computer attached to the engines, hoping to see an error code getting thrown. No error code is displayed.

Has anyone heard of something like this? Any idea what can cause this? If the boat sits running at idle it will not shut down, only when it is under load.

Any help, suggestions are most appreciated.

Thank you.