I replaced the water impeller last week and that did not fix the problem. When the boat idles at lower rpm eventually the warning buzzer goes off, to get the buzzer to go off I have to drive the boat then it quits. I was wondering what it could be ,I'm leaning toward a bad thermostat on one of the powerheads,but why would it go off at low RPM and clear when you drive it at higher RPM. The owner of the boat said that the pressure gauge on the dash has failed (high) but that happened a couple years ago and it did not affect the warning buzzer.Also is there a pressure sensor for the cooling system on this motor? Any help is appreciated.:|