2008 360 Express with 350 Yamahas (700 hours). Boat just had its 100 hour service and on the first run after service, the starboard motor began losing RPMs at higher rpms (4800). It was dropping into the low 4000's and upper 3000s. Lower RMS ran fine. Port engine was fine. . Never had this problem before, or any engine problem before for the matter. Am I correct to assume this is probably related to a VST/fuel filter problem related to the service? Thanks.
Losing RPMs
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SeanC
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- Location
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- Seafarer
Check your fuel lines first. Had similar problem and turned out to be a kinked fuel line coming off the small fuel/water separating filter attached to the motor.
If you have a fuel filter with a clear bowl, remove it and re-install paying attention that the upper lip is seated correctly and completely. Those bowls often get skewed or a bit oval and you end up sucking a little air. At low rates it still runs ok but as gas demand goes up, the motor starves.
The water separator filter may also be sucking air. That can happen when some of the old gasket sticks to the flange which of course you can easily see but you can feel it.
The water separator filter may also be sucking air. That can happen when some of the old gasket sticks to the flange which of course you can easily see but you can feel it.
Replace the spark plugs or check them. Had the same thing happen to my 2006 330 Express 3 weeks ago - one engine fine and the other wouldn’t get over 3800-4200 rpms. Went back to dock and changed the spark plugs and all was ok. Could be something else but check spark plus or replace if you haven’t done so this year.