Warning alarm when running boat hard. 2004 Yamaha 250 ox66

[BigStickFishing]

Like the title says my warning alarm comes on when I am running WOT. Motor is on a Skeeter ZX250 and runs like a top when I keep it under 5,000 rpm's. When I try to run it wide open it runs for a short period of time then the alarm goes off with a constant alarm. Then the motor starts going into guardian mode and slows down. The motor never dies and after idling for about 30 seconds the alarm does off and will get right back on plane and run great up to 5,000 rpm's. My question is what are the things the alarms will go off for on a Yamaha and where could I start looking for issues?

2004 Yamaha 250 ox66
Serial# VX250TLRC

[yam911]

Two events normally set the alarm. Over temperature and low oil in the engine mounted main tank.

Too bad you do not have a Yamaha tachometer that will tell you what is causing the alarm.

As soon as it happens I would shut the motor down. Remove the cowling. Try and determine if the motor seems to be hot. At the same time, inspect the main oil tank. Is it full or is it low.

[Chrisj.01]

When it goes off, check the oil tank on the motor. I bet your remote oil tank in the boat needs a new filter. If it has anything to do with oil and not temp.

[yam911]

When it goes off, check the oil tank on the motor. I bet your remote oil tank in the boat needs a new filter. If it has anything to do with oil and not temp.

Exactly. A restricted filter, a failing weak pump, or defective wiring can all cause the oil transfer system to not be able to keep up with the demands of the motor. Tank runs low, alarm sounds, by the time the user gets around to checking things out the transfer pump might have refilled the main oil tank. Or filled it enough so that the alarm stops.

[Circusboy]

When my 250 let go it was at WOT. Trimmed out, the bow rode high, 22' aluminum bay boat. the oil in the remote tank ran low enough that the angle of the boat, high bow, kept the oil from tank outlet. This caused the small oil tank on the motor to run dry. Broke the crank and damaged 2 pistons. The motor would idle but sounded like a diesel. The motor was so loud and the wind noise kept me from hearing the alarm. Hope this helps and good luck

[21XDC]

I'd feel the pisser when it does that. If it's hotter than usual, I'd look at a water pump, T-Stats closed, and temp sensors on top of the block. There are 2 of them. I had one that went bad and set off the hot alarm and the motor wasnt hot... I replaced both and all was well. I tested them in a pot of water on the stove with a continuity tester and thermometer.

[yam911]

When my 250 let go it was at WOT. Trimmed out, the bow rode high, 22' aluminum bay boat. the oil in the remote tank ran low enough that the angle of the boat, high bow, kept the oil from tank outlet. This caused the small oil tank on the motor to run dry. Broke the crank and damaged 2 pistons. The motor would idle but sounded like a diesel. The motor was so loud and the wind noise kept me from hearing the alarm. Hope this helps and good luck

Did the motor fail to go into RPM reduction mode? It should have done that at the same time that the alarm was sounding. Long before the motor suffered from oil starvation.

Had there been a Yamaha tachometer installed you would have also been given notice that the remote oil tank was running low.

Sounds like the old adage "for want of a nail a shoe was lost, for want of a shoe the horse was lost".

[Circusboy]

i was prop testing earlier that day. Ran the oil low. It was my fault 100% for not thinking about how much oil it used. No warnings just 6000 RPM screaming and It just shut off. Brand new boat, old motor.

[CJ1]

Check your intake screens, be sure they are flush with the case. Sticking out even a little bit can cause cavitation at high speed. Along with what everybody else is saying. CJ

[DennisJensen]

What's your water pressure at?

[BigStickFishing]

OK guys sorry for the late response. I have replaced the filter on the oil tank and still goes into guardian mode when running Wide Open for two or three minutes. As soon as I slow down buzzer goes off and motor runs like a top. Still will run at 4,000 rpms all day and buzzer will never sound. Any recommendation on what to replace next. I am interested in replacing everything just to be on the safe side as I am not sure what the owner did before me.

[bassboat1]

If it's overheating, could be thermostat(s), poppet valve, head gasket, water jacket obstruction, intake screen, maybe temp sensor.

[yam911]

Was the oil transfer system ever tested?

[yam911]

OK guys sorry for the late response. I have replaced the filter on the oil tank and still goes into guardian mode when running Wide Open for two or three minutes. As soon as I slow down buzzer goes off and motor runs like a top. Still will run at 4,000 rpms all day and buzzer will never sound. Any recommendation on what to replace next. I am interested in replacing everything just to be on the safe side as I am not sure what the owner did before me.

CDI assembly
Main oil tank
Main engine wire harness
Remote oil tank
Wire harness from motor to remote tank
Lower unit
Water pump
Water pump transfer tube
Water inlet screens
Pressure control valve
Thermosats
Thermoswitches

[McQuaig]

Could it simply be engine height (PTP) to high? 5000 rpm ok, but 6000 rpm could be just enough to gain enough height to lose water pressure, especially if you trim up a bit???? Might be worth dropping it 1/2 inch or more to try...

[1ranger487vs]

Did I miss the actual water pressure. Don’t think he ever said. I also ran a temp gauge on my ox66. Wasn’t the best setup but it worked

[BigStickFishing]

I talked to Jason this morning @ JTM Outboards and he seems to tink its an overheating problem. I am doing to check my ptp and lower it a 1/2 for starters.

Water pressure gauge is broken replacing it after work.

Will have new info after testing this weekend.

[Skeeter Jeff]

If you have good water pressure, its a water flow issue. On my 97 ProV that would only alarm at 5,000 rpm, I replaced the thermostats, pressure control valve and both the thermo switches. When I tested the existing parts, the thermostats where very slow to open, the thermo switches also were inconsistent in the readings I measured.

I run in only fresh water and I was amazed at the crud that was on the thermostats, covers and control valve. I replaced these parts to rule them out... and cleaned everything the best I could. The next option was to remove the heads and clean out the water passages but this fixed my problem.

[04_triton]

When it goes off, check the oil tank on the motor. I bet your remote oil tank in the boat needs a new filter. If it has anything to do with oil and not temp.

Where would this filter be located?

[yam911]

Where would this filter be located?

Remote oil tank.