2004 Merc 40 ELPTEFI surging issue - help needed

skimtb

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Jun 22, 2015
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New boat / motor to me last year. No issues, other than I changed the voltage regulator per a recall / update. Ran great all year.

Not sure if it matters, but it is a Bigfoot series / model.

2nd or 3rd time out this year, if run wide open (5000 rpm) for 2 minutes, it starts surging, maybe 2500 rpm - 4500 rpm back and forth. If I drop to 4000, same thing. If I drop to 200-2500 it goes away, and I can run slower for a while. I went back to 4000 and it started doing it after a minute or two.

Any suggestions? I have not done much with this one yet...

My initial thought is to go after fuel filter(s) and see if that does it. We have had a A LOT of rain this spring, so I'm also wondering if there is water in the gas, I may throw some dry gas in too. Draining / refilling isn't very practical, It is on the water.

Thanks.
 
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