SmartCraft throws a "water pressure" alarm.

[Old Man In The Sea Ray]

Greetings,
I have a 2002, 270 Sundeck, 496 Mag HO, (fresh water cooling). I'm a decent mechanic and do my own work. I installed a thu hull fitting, before the water pump, when I got the boat eight months ago. She always runs right at 175 degrees, never any problems.
It's my understanding that the SmartCraft water pressure monitor is designed to throw an alarm if water pressure gets too low.
With the display set on "low water pressure" it shows about 3 psi at low rpms (1500ish). Temp gage reads 175. When I accelerate, I can watch the display rise to 5 psi and then it throws the alarm... temp gage still at 175. If I immediately turn the key off and restart, the alarm stops and everthing is fine until I nail it again.
I'm lost. Any help greatly appreciated.
TIA
Russ Lukens

 

[Jimmy Buoy]

I'd say the pressure readings should be 3-5psi at idle going as high as 25-30psi full tilt. Accelerating to more than 3000rpm should develop more than 5psi. It may be that the raw water pump impeller is wearing to the point where the vanes collapse when spun at higher rpm. My last boat had twin 8.1s (same motors) and it ran at 160. Lack of water pressure and flow may be causing yours to run at 175.