I’ve been trying to think through a slight problem with one of the Yamaha F250’s on my center console. For the past several weeks I feel a slight stutter in momentum when the outboards are under load. There is no noticeable change in RPM’s or even sound, but it feels like slightly running over a mud flat…but only for a fraction of a second.
The stutter is timed pretty regularly but may vary depending on the RPM load. At WOT the stutter is either unnoticeable or non existent. It can be felt more prominently when the boat has not been run in awhile or early in the day before the motors are really warmed up.
I’ve run on each motor independently and determined it is just the port motor. As of the last week I’ve done a full service (motor oil, filter, water/fuel seperators, water pumps, lower unit oil) and the stutter is still there.
My first inclination is a fuel problem somewhere but really thought the water fuel separator would have resolved it.
Hoping someone out there has had a similar experience or others with more experience can help me think through potential causes and solutions.
I completely recognize that this is a difficult diagnosis so really appreciate any advice!
Having the exact same issue with one of my F250s. Last time this happened my fuel injectors needed cleaning. It’s in the shop now. Will let you know what they say…
I’m with Chris V! Had that same problem once on my twin Mercs, it turned out to be a slightly dinged blade on my port motor! Good luck, hope you find the problem.
That was a suspicion of mine too, i haven’t really examined it yet though because the stutter would happen really pronounced on lower RPM’s and earlier in the day. Dwindling to almost unnoticeable by the end of the day. Perhaps I just get conditioned to it…I’ll pull the prop this weekend and check it out. Thanks for the advice!
Had a friend with 225 motor, same problem, chased everything $$$, on a fluke, a mechanic unplugged the idle air valve, problem stopped. 25$ part, 6 months: computer hookups, fuel injectors, pumps, 3 trained yamaha “experts”, everything, almost gave up. Promised him I would pass this along.