Warning Buzzer At High Rpm's

[Res2que@]

Hello All, Twin 2002 225 Yamaha
I had a 40 mile run and was running 3200 rpm, then sped up and started getting a buzzer at about 4000 rpms ...brought it back down to 3200 and no alarm buzzer. They ran perfect other than the buzzer

I did it a couple time and it kept doing it....Ive had the engines checked and there are no codes.

Any ideas on whats causing this
Thanks

[99yam40]

What were your gauges telling you the alarm was?
a complete model # may help others know exactly what motors you have

[Res2que@]

F225TXRA.....NO Guage warning

Not sure what YDS is??

[boscoe99]

By no gauge warning are you saying that you don't have gauges installed that show what the warning is about or that gauges are installed but there was no indication on them as to the warning.

As to the cause of the warning it is either low oil pressure or over temperature.

YDS is short for YDIS which is Yamaha Diagnostic Information System. Via a PC and Yamaha software engine data can be extracted and see on the PC. If a code was set you will be able to see it.

But something is strange in that if the buzzer sounds both motors should have gone into RPM reduction mode, which you make no mention of it happening.

[Res2que@]

I had both motors checked at the dealer last week ...they ran a complete diagnostics and came up with 0 codes

[Res2que@]

I have the guages ...but there was no indication on them.....motors did not go into safe mode
....They ran perfect...other than the buzzer

[Res2que@]

If anyone has any ideas please let me know....Thank you for responding

[boscoe99]

Are you absolutely, positively, 100% sure that it was the buzzer that you heard?

[rodbolt17]

all F225 motors can be looked at with YDS they can also display active codes with the diagnostic test lamp.

it may not STORE the code.
the oil pressure switch can fail,it can be either low or over pressure.

if either temp switch closes but the CTS is in range you get a tone with no alarm display.
temp switch operation can be monitored with YDS, or a multi meter .

[Res2que@]

Thank you i will try all that advice......im not sure what else the sound would be or could be other than an alarm boscoe....do you have an idea.....its a Grady 273 chase

[99yam40]

I believe Rod has it, even thou I cannot remember what CTS is(some temp sending unit maybe).

Possible you have some build up in cooling channels and running higher RPMs causes more heat then the cooling flow can remove closing a switch or water pumps need servicing.

Or like the others have said oil pressure

[boscoe99]

I believe Rod has it, even thou I cannot remember what CTS is(some temp sending unit maybe).

Possible you have some build up in cooling channels and running higher RPMs causes more heat then the cooling flow can remove closing a switch or water pumps need servicing.

Or like the others have said oil pressure

I think when he uses the term CTS he is referring to Coolant Temperature Sensor. Which really is not a sensor but a thermistor (heated sensitive variable resistor) with a negative co-efficient.

If an oil sensor is not really a sensor, but rather is a switch, then a cooling sensor cannot be a sensor either. I suppose. grin

[rodbolt17]

on the F225 the oil pressure sensor is a sensor.
it has a 5V reference and a ground with a voltage "pick off" to tell the ECU what the pressure is electronically.

the ECU is also looking at RPM.
the ECU is "mapped" so that at a given RPM the OPS voltage should be X value.
if the value is higher OR lower than the RPM map then the buzzer is set and RPM reduction should occur if above about 2500 RPM.
for temp the F225 uses two switch's AND a coolent temp sensor.

if either temp SWITCH closes the buzzer will sound,after a delay, if the CTS agrees with the closed switch you get RPM reduction and a visual indicate.
I don't design this stuff I just have to know how it works so I can fix it when its broke.
incorrect battery voltage,water in the fuel(if equipped) low or high oil pressure,over temp can all set the buzzer on that motor.

[99yam40]

since he stated he did not get RPM reduction when the alarm came in at 4K that should rule out oil pressure.

not sure about water in fuel cup as that is only in gear alarm but do not see how reducing RPM would make it go away.

And I do not understand how voltage could change between 3200 and 4000 to cause the alarm .

My bet is still on overheat that CTS and switches are not agreeing on

Hooked up to a computer while it happens sounds like the correct way to see

[rodbolt17]

sensors fail, last one I did showed 140 PSI at 4200 RPM,alarm,RPM reduction and the oil visual lit up.

its mapped target at that RPM is about 85 PSI.
if you look at the manual for the F225 3.3L it will say low oil pressure on-variable with engine speed.

the water detect was not an engine option on that model. it was however an option for the water separator in the hull. that's why I said IF equipped.

they also break very easily
instead of switch sheet simply run it until it alarms with YDS attached,hit save when the alarm is on and it saves the past 13 min of run time in 1 minute blocks.
I like properly testing/trouble shooting. I DO NOT like switching things.