1988 90hp warning buzzer

[hooked1]

Hi l,m new to this forum as l have just purchased this boat and motor, the trouble l'm having is at about 4000rpm the warning buzzer goes off and l'm not sure what it is, l did not receive a manual of the motor on purchase so if someone has one in pdf it would be greatly appreciated.
l have noticed that their is a green light that is on showing oil full, which l didn't notice before.Any help or guidance appreciated.
Regard Jason
email address is:curmi72@hotmail.com
Thanks and safe boating

[Ken]

Jason,
The warning buzzer is most probably going off because of an overheat signal from the thermo switch. The thermo switch is designed to close at around 180 degrees f. to signal the ignition control that an overheat condition exists. Two things happen - the warning buzzer goes off and the motor goes into rpm reduction mode - the motor shakes violently because the ignition has cut back on the spark.
You probably have a weak water pump, and therefore low water pressure. If it has been at least three years since last water pump repair, I would recommend it. Also, the thermostat could be sticking and not allowing enough cooling water to enter the water jacket of the head. Or the thermo switch itself could be faulty and closing prematurely and giving a false overheat condition.
Both the thermostat and the thermo switch can be removed and tested in a pan of heated water. You really need a Yamaha service manual to guide you along. Go to www.yamahapubs.com to order online.
Good luck [img]smile.gif[/img] ,
Ken K

[hooked1]

Thanks Ken

Regards