whining noise in throttle

[Flydaddy]

Greetings. I have a 115 hp Yamaha 4 stroke on a 18.5' aluminum boat. Built for fishing and hunting, but regularly misused for pulling kids on skis and tubes, so the throttle is used/abused a lot powering up and down. Was pulling kids the other day when a loud whining noise began. Sounds very much like it's coming from the throttle. Powered down and turned off motor, waited a bit and cranked it and the noise had stopped, but it happened another couple times so I stopped using for fear of burning something up. It seemed to also affect the power in the motor, but I didn't run it long enough to tell for sure.

Also, on occasion, the motor will go from full power to nothing. It's still running, just no juice for a minute or two, then it'll go again without any restriction. Water in the gas or something maybe?

Any suggestions for something I can check/repair on these issues myself? All local boat mechanics take months. Thanks!

 

[99yam40]

sounds like the motor is overheating or oil pressure is out of spec.
the noise and the limiting of RPM is to let yoou know the motor has a problem, and you need to look at your gauges to see what they tell you.
and shut down when safe to do so.

 

[jimmbo]

Welcome to iboats

Motors make a variety of Noises, even when running fine.
"A loud whining noise", is very vague. "coming from the Throttle" ??? Throttle Control, Throttle Linkage, Howling sound from the Inlet?
Going from Full Throttle to idle... and the Throttle Control is still set for WOT?

 

[Flydaddy]

Welcome to iboats

Motors make a variety of Noises, even when running fine.
"A loud whining noise", is very vague. "coming from the Throttle" ??? Throttle Control, Throttle Linkage, Howling sound from the Inlet?
Going from Full Throttle to idle... and the Throttle Control is still set for WOT?

Thanks. This is not a normal noise. Whining was a poor choice of words. It's more like a loud screeching, like a bearing going out or something running without sufficient fluid.
On the other issue, yes throttle control is set for WOT and it suddenly loses all power.

 

[Flydaddy]

sounds like the motor is overheating or oil pressure is out of spec.
the noise and the limiting of RPM is to let yoou know the motor has a problem, and you need to look at your gauges to see what they tell you.
and shut down when safe to do so.

Thanks. Tacometer works, but none of the other gauges do. That's on my list to fix. I'll check the oil pressure.

 

[jimmbo]

A Screech is a lot different from a Whine. Are there any V-belts on that engine, like for an Alternator? A dry bearing will certainly Screech if starved of Oil. Is the Oil Level correct? Oil Starvation will throw the Motor into a limp mode.
None of the Other Gauges work, so any and all warning lights if any, are not functioning either?
How long have you had this motor?

 

[lakensea]

IT'S THE WARNING ALARM!!
Have you read your owner's manual?
Keep driving it with the alarm going off and you will discover what the problem is (was).

 

[boscoe99]

Sounds like you have a 703 side mounted remote control box. The warning horn/buzzer is located within the control box.

When you hear the horn, stop the motor immediately. There is no failsafe mode. Keep operating the motor with the horn whining and you can ruin the motor.

A reduction from high RPM to low RPM without the throttle being retarded can indicate that the motor has put itself into the RPM reduction mode. Another indication to stop the darn motor. RPM reduction mode and the horn generally happen at or about the same time.

To hear what the horn sounds like, pull the kill switch lanyard. Then try and start the motor. The horn will sound. The motor won't start.

 

[Flydaddy]

Thanks for all the replies. Impeller was bad. $30 fix.

 

[99yam40]

just replacing the impeller may not be good enough.
most replace the whole pump with a kit and maybe the housing also.
and where did all the pieces of impeller go if they came apart?
you may have pieces up inside the motor plugging up passages.