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

[MarGig]

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!

 

[Levinz11]

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

Does it do this automatically during break-in?

 

[MarGig]

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

Does it do this automatically during break-in?

The mechanics at the dealership had already done the break-in for me before delivery. I'm no expert on this, but don't think there should be a reason for it to cut out automatically during the break-in, though.

 

[proudmary]

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

I had a very similar situation with my brand new Yamaha 40 hp last year. Turned out to be the negative battery cable to the motor was not torqued down properly when rigged. Felt like a fool - too me 2 weeks to find it.

 

[MarGig]

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

I had a very similar situation with my brand new Yamaha 40 hp last year. Turned out to be the negative battery cable to the motor was not torqued down properly when rigged. Felt like a fool - too me 2 weeks to find it.

I just got a call back from the mechanic and, amazingly, that's exactly what he said had happened. Due to the loose wire, when hitting a couple of decent sized waves at higher rpms, the electronics in the motor would loose juice and shut down. He claims that it's fixed and his last sea trial went smoothly.

Thanks for your help!

 

[Capt Ken]

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

Actually a fail safe system built into the electronics. Doesn't sound the alarm but does throw it into the safe mode

 

[99yam40]

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

I thought low voltage would alarm and not set safe mode on some motors, but never heard anything about the F300.
Edit: Well come to think about it, I think I have heard of not having enough voltage to control everything so it just shuts down on these newer motors

 

[Capt Ken]

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

Yamaha started doing that on the larger engines back in the 90's. Called "Loose Battery Fault". Some engines will sound the alarm but most won't. Yamaha engineers do weird things like the water in fuel alarm will sound in neutral but will silence when you shift into gear. WHY? I guess it's to keep us techs guessing.

 

[MarGig]

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

I thought low voltage would alarm and not set safe mode on some motors, but never heard anything about the F300.
Edit: Well come to think about it, I think I have heard of not having enough voltage to control everything so it just shuts down on these newer motors

Yup, that's exactly what they said was happening.

Took the boat out last night and it worked fine. Had a blast...

 

[Geem03]

I have a 2017 G3 pontoon with a f70 Yamaha outboard. This season, with only 37.5 hours on the motor, it started to quit. Exactly to the T of everything that you have described. The dealer and I were stumped! They spend 13 hours on the boat , and we're not able to come up with anything. Like you had said, there were no codes, no alarms and it didn't matter at what RPM really . I just want to say thank you! My negative cable battery was loose and had oxidization on it and ever since we cleaned it up and tightened everything, the boat has been running fine. We are hoping that this was the issue and so far, it seems that it was. I searched for hours and hours on the internet for problems with the f70 and could not find much on it except that people ranted and raved about what a good motor it was.