shop manual for 90hp ELPT 2 str ot087666 '99. water pressure?

[donf]

I've got '00 Mercury 90hp ELPT 2 stroke. s/n ot087666 built in '99. I have the genuine Merc shop manual but it covers lots of stuff from 75 hp and up including the jet drive versions. Is there a more detailed specific to my motor shop manual that I can buy? My question right now is where is the spot to tap into to monitor water pressure?. Is it where that brass plug is on top of the head next to the spark plug? How high will the water pressure go under wo throttle? At that spot I'm reading like 10 psi.

[JOE54]

brass plug , 10 is minimum at 5000

[donf]

tks Joe. Sounds like my readings and attach point are correct. I see water pressure get higher than 10 and then drops off quickly. Must be the "pop off" valve. Always a strong spray out of the tell tale.