25hp Idling problem, Thermostat or CDI?

[se bill]

I have a 2003, 2-stroke, 25hp yamaha.

At what seems to be absolutely random timing, it will cut out to idle while running. Sometimes at the beginning of a trip, sometimes at the end. No alarm goes off, it just cuts out to idle (The only constant is that I am usually at high rpms when it starts). I've had it happen on a short 10 minute ride, and then the next day, I'll run it wide open for an hour or two and its fine. Other times its the opposite.

It is my understanding that my motor has a built in feature that causes it to cut out to idle if it starts to overheat (its also supposed to have an alarm). However, I am fairly certain that its not actually overheating.

My question is, does the thermostat have the ability to force the motor to idle, or is that something that is decided through the CDI?

I couldn't see any wires going from the thermostat to the CDI on the wiring diagram, but I could be mistaken.

 

[robert graham]

Re: 25hp Idling problem, Thermostat or CDI?

most probably a fuel delivery issue. check entire system starting from tank pick-up check valve, hose fittings, primer bulb, quick disconnect on motor cowl, fuel filter, fuel pump, then if you don't find it, drain/clean carb. a small leak can allow air into system. Good Luck!

 

[99yam40]

Re: 25hp Idling problem, Thermostat or CDI?

The thermostat opens and closes to regulate the water flow and tempature of the motor. There is a temp switch or temp sending unit that tells the CDI if it is getting too hot. Should be the one with the pink wire and black wire on it. If the motor is oil injected it can go into safe mode from oil problems or temp. You need to check your manual and test the alarms.