1995 Merc XRi v6 no spark on one side

[B Robinson]

Posting for a friend. Here's the scenario he lays out for me.
Bought a boat that sat for 3 years. Took it out, ran fine, everything seemed good. Bring it home, installs a structure scan ducer, and after that, no spark on cylinders 1-3-5, one entire side. Makes no sense. I think it's just coincidence that he found the problem after installing the ducer, but that's what he tells me.
Buddy came over with a spark tester, they changed out some CDI boxes, and still nothing. Any idea on what could have happened or where to start looking? Thanks for any info.

Brian

[JOE54]

unplug red white pig tail wire on outside box and white black pig tail from inside box go to idle stabilizer poss bad , do it report back

[B Robinson]

Well, they switched some wires like you said, did some switching of the CDI boxes or too, not quite sure, but as they were testing for spark, it fired right up, ran great. I just hope it continues for him. Thanks!

[JOE54]