F115 Hiccups at higher RPM

[stech115]

Hi Guys!

Just bought myself a 2003 Yamaha F115 Four Stroke with only 250hours.

The engine is easy to start, and sounds very good on both idle and at higher RPM.

But when i reach about 4000RPM and higher the engine suddenly cuts for a second or so, before it goes back to normal operation. The engine warning light starts blinking at my Tach instrument.
I did just receive my Yamaha Diagnostic eqiptment, but havnt had the time to try it yet.

Is there any ideas, or previous experience with this problem? I have also bought a new bigger battery (needed a replacement anyway).

[Jason2tpa]

The engine warning light starts blinking at my Tach instrument. .

You've got two visual alarms on the tach, low oil and high heat. Which one is blinking? My guess is the low oil. Either way, you could have a short in the tach's wiring causing a false signal. If you actually had a low oil problem the alarm would remain on and you wouldn't be able to throttle up over 2k. From your words it sounds like you could cruise at 3k rpms forever. Well you couldn't if there is an low oil alarm.

At first I'm thinking it's a carb jet issue with the hesitation at top end, though the warning blinker is throwing me off. Hang tight on here. A few of the pros will chime in soon.

[stech115]

You've got two visual alarms on the tach, low oil and high heat. Which one is blinking? My guess is the low oil. Either way, you could have a short in the tach's wiring causing a false signal. If you actually had a low oil problem the alarm would remain on and you wouldn't be able to throttle up over 2k. From your words it sounds like you could cruise at 3k rpms forever. Well you couldn't if there is an low oil alarm.

At first I'm thinking it's a carb jet issue with the hesitation at top end, though the warning blinker is throwing me off. Hang tight on here. A few of the pros will chime in soon.

No, its not oil warning, it is engine fault indication. Same as in your car.

[fairdeal]

well, get that YDS hooked up and tell us what you've got for "Diagnosis Record"

[rodbolt17]

we can rule out carb jets.

the check engine warning is normally a low voltage issue.

[Jason2tpa]

we can rule out carb jets.

the check engine warning is normally a low voltage issue.

Im not familiar with that tach now he's posted the pic. Interesting though, why would he be experiencing a low voltage alarm only at 4k rpms and not get the alarm below 4k? I would think he'd get this alarm immediately after starting engine.

[greasyshaft]

Im not familiar with that tach now he's posted the pic. Interesting though, why would he be experiencing a low voltage alarm only at 4k rpms and not get the alarm below 4k? I would think he'd get this alarm immediately after starting engine.

Rodbolt never said that it was a low voltage alarm. Think of what will happen when you have have low voltage supplied to a sensor circuit, or a sensor that is shorting out.
Also at higher rpm's the injectors and ignition coils are all drawing more current due to the increased firing frequency.