New Yamaha F300 motor cuts out at mid/high RPMs - Help!

[MarGigUri]

Hello all,

Just picked up my new boat this past weekend and took it out for the first time yesterday. The boat has a new Yamaha F300 4-stroke. About 20 minutes after leaving the marina, when I got the motor above 3000 RPMs, it suddenly cut out and brought us to a sudden halt. I was able to start the motor again immediately and it performed as if nothing had happened. A few minutes later, it cut out again. Over the course of 2 hours, it cut out about 10-12 times, always at RPMs higher than 3000 and it always started again without any trouble. It feels like an electronic malfunction, because the motor sounds and behaves fine otherwise.

I dropped it off at the dealer today, but he claims the motor worked fine when he sea trialed it today. Am obviously not happy because it's a brand new motor, but there's no way I'm letting the dealer send me home with the boat unless he confirms he found the problem and fixed it. Any suggestions on what could be wrong with it or how I can point the mechanics in the right direction?

Thanks!

[boscoe99]

How does a mechanic fix a problem that he cannot find?

Intermittent problems are the worst.

[Sequoiha]

if it occured with you 10 to 12 times and he cannot duplicate it, go for a ride with him.. almost sounds like a fuel restriction to me. once the vst runs out of fuel and the lift pump cannot supply enough it will cut out like that, then when you bring the throttle back and restart the motor the lift pump has time to fill the vst. ill bet if you keep it at low rpm it will run fine for quite a while..

[tmann45]

Its the electronic nanny cutting the fuel when you exceed recommended break-in RPM :-)

[99yam40]

I also wondered if you are following the breaking procedures.

But I have no idea if the motor will force you to keep RPM below any certain level during break in.

Dealer should be able to check fuel flow to be sure the system can flow enough to feed motor properly

[Sequoiha]

I also wondered if you are following the breaking procedures.

But I have no idea if the motor will force you to keep RPM below any certain level during break in.

Dealer should be able to check fuel flow to be sure the system can flow enough to feed motor properly

no, break in will not limit the rpms... being a new boat it is probably a kinked fuel line or something like that.. if it has a installed fuel water seperator, ive seen people use teflon tape and it covers part of the hole causing poor fuel flow..

[rodbolt17]

your describing a classic fuel restriction.
Yamaha makes a boat fuel system tester.
your dealership should have one.
best thing to tell the mechanic is nothing about the internet.
I usually give customers one warning when they start telling me what they read on the net.
second time I tell them to let the net fix it.
I currently have a customer that's getting ready to get the boot over the net mechanic thing.

[captain rednut]

how did you go with your problem??

Any update or solution found with your problem?? curious as i had a new f250 do this and it was loose pins in the main loom causing the problem.