Water pressure fluctuating

[propspin]

1984 V150 Mercury. Just put in a new water pump. I have 11 psi at idle (engine in a large bucket) however if I run the engine to 1000 RPM, I get a fluctuating water pressure, needle bounces from 0 to 12 psi, also the tell tale stream fluctuates. I have removed the poppet valve, everything looks ok. I have recently taken the engine out of storage, but I remember having the fluctuating pressure problem before, while on a slow plane and the engine trimmed down.... trimming the engine seemed to make the fluctuation go away. Any thoughts as to why this is happening? btw, what should the water pressure be?

thanks

 

[Bondo]

Re: Water pressure fluctuating

Ayuh,... How old is the impeller,..??

 

[j_martin]

Re: Water pressure fluctuating

Ayuh,... How old is the impeller,..??

Ayuh, first line says brand new.

10 lbs is high at idle, and would indicate plugged passages in the engine. Be sure your meter is on the peg when the engine is off before you believe it.

Be sure the gauge line isn't being kinked by the trim action.