Help! Engine overheat alarm on Yamaha 2000 Ox66 225HP

[Boater93]

Help!
I'm pulling my hair out trying to fix my Yamaha 2000 Ox66 225HP - engine overheat alarm goes off at slow speeds.
- I have replaced: water pump, PRV, thermostats, cleaned the 02 sensor
- The alarm goes off at no wake speed within 5 -7 minutes after leaving the dock, or coming back from the lake. It goes off at the same place in the channel.
What do you suggest?

[99yam40]

did you use OEM parts when you replaced all of that?

did you replace water pump with a kit or just an impeller?

[Boater93]

Yamaha parts
Replaced the entire water pump kit

[99yam40]

did you see any melting of the plastic housing?
and did you install the rubber dampener onto the housing where the tube its into?

sounds like the pump is not getting enough water into the power head at low RPM

[Boater93]

Good questions. I will confirm.

[Boater93]

How can you tell if its overheating? I have a heat gun. Even when the alarm is going off the temp is the same as the other engine. (I have a 2870 Pursuit with twin 225's)

[G3yamaha]

I had this problem about 6 years ago, and did 2 things recommended on this forum at the same time (unfortunately I don't know which one worked):I stretched the poppet valve spring just a bit to increase the spring strength and increased the idle speed very slightly. I ***** for hours at idle with no issues ever since.

[G3yamaha]

Edit: a different forum. https://www.thehulltruth.com/boating...ting-ilde.html