I can comment on this since my tournament partner has had two different XS motors, 08 and 09 with the exact same intermittent problem. Mercury replaced the “bad” coils on first motor at roughly 50 hrs. Boat would take forever to plane off. I think it was only two of the six, I just remember that he was upset they wouldnt replace them all. At 100 hours, had the same problem and they replaced all six. He didnt keep the boat long enough to see if it truly fixed the problem.Second motor, 09, has had the coils replaced twice, all six. Still had the same issue but only periodic, but the boat would not plane at all when motor bogged. Strange thing was if it bogged, you could throw it in reverse and rev it up, put back in gear and everything was fine… They replaced the fuel rails about 40 engine hours ago and it appears to have resolved the issue. Each tech at two different Mercury shops immediately said it was the coils… not sure how to test a fuel rail, but you may want to look at that as well.
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