Any ideas?

Sweatliner

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Was heading back in last week and at WOT it started to cut out. I opened the gas tank cap a little thinking it needed to vent. Vent on this tank is temperamental. Nope. Runs great at idle up to 1/4 throttle then it cuts out. Doesn’t die just bucks all over. Sure seems fuel related to me. Replaced the tank, new fuel line and primer bulb from tank to outboard connection. New gas. Fuel filter looks good. Briefly took it out and same. Starts right up, idles perfect, slowly throttle up to 1/4 it’s fine. Anything past that and starts cutting out. Tried squeezing the primer bulb while accelerating and same cutting out. Fuel lines look good, although they sure are wedged in there with seemingly tight turns. Unbent the lines while running and same deal.

2019 Yamaha F25 EFI

It’s been flawless until now

Thanks for any help
 

Rubberhead

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It sounds like your rev limiter is kicking in. This usually happens when there's an alarm like a overheat alarm. It doesn't sound like you're overheating so the sensor might have gone bad. Could be a low oil sensor too if your running a 4-stroke or oil-injected 2-stroke.
 

creedsduckman

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I've got a 2011 40 Yamaha that has done the same thing to me, or so it sounds like. One time it had a bad coil. The other time it just needed the vst cleaned out. There is a internal filter in there I believe. The mechanic that did it showed me a cup of gas that came out of it that had tiny black specks in it. He said it was the fuel line breaking down, yes it was ethanol resistant fuel line. He recommended replacing the fuel line every other year. I have ever since and haven't had that problem again.
 

creedsduckman

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Do what I do......run non ethanol gas if at all possible.
Much easier to just replace the fuel line every other year. All I've ever used is ethanol gas, keep startron and ring free in it and don't let it get old.
 

metalworx

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I'm fortunate enough to have a gas station in town that sells non ethanol gas. I put ring free and fuel stabilizer in both my Yamaha four strokes. I have had zero issues with fuel lines breaking down.
 

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