Warning Buzzer on 1999 Yamaha F100

[MNBIGBEAR]

ok, the problem I am having is that when I run the motor at anything above 4500 rpms for any length of time, the warning buzzer sounds and the motor goes into safety mode. There is plenty of oil and the motor is spitting out water. Also, as long as I run the motor around 4000 rpms it runs smooth with no problems. I have read other numerous posts and I have been trying everything.

I cleaned the battery terminals, changed the oil filter, backflushed the cooling system and checked for loose wires.

My boat does not have the digital gauges so I am unaware if this is something related to the oil pressure or overheating.

Although the last time the buzzer sounded, I immediately took off the cover and put my hands right on the motor and it did not feel hot to the touch so I am assuming it is not overheating. Which leads me to believe that it is something to do with the oil pressure.

Could this be a bad sensor? Or could it be a weak oil pump or something. Ive called a few different shops and they all give me a different answer so I am leary that the problem wont get fixed unless I can nail it down prior to bringing it in. ANY suggestions? (Sorry about writing a book)

[reddog]

I just went thru the exact same thing, for the last 7 weeks with a F115.

Diagnostics showed no codes.

Oil pressure and water temp were fine.

Spents several weeks in the shop.

Finally got it fixed on Thursday, after spending a couple hours on the water with the dignostic computer hooked up.

Bad ECM board.

Expensive to repair, but I dont care if its your employees, your outboard or your wife, if you cant trust it its not worth owning.

Havent gotten the bill yet, but the number $1100.00 for the ECM was mentioned a couple times.

[Northlander]

OUCH!

[MNBIGBEAR]

That would really sting....I did buy a water pump rebuild kit with a new impeller. Figured I would start there. Should be here in a day or so. Now im really crossing my fingers that this will take care of it. By the way, I did a little more checking and the water stream seemed a little weak so im thinking it may be an overheating problem.

[Wanderer]

Good chance the water pump is your problem. I had the same problem with my 150 a while back.

The new impeller took care of it.

Good luck - be optimistic!