1989 evinrude 200stlceb water pressure help

[Gsmith223]

I have a 1989 erude 200 xp outboard on a 1986 1950v procraft. The boat has a water pressure gauge but it is not hooked up . I found a tee in a cooling line between the control valve and a fitting on the bottom of the block on the drivers side. The T had been plugged so I used it for the pressure gauge. It looked like a spot for either the factory pressure gauge or speedo.
With the motor running on the muffs at idle I get about three pounds of water pressure.
My question is am I tapped into the right line to get the proper water pressure reading? Also what water pressure should I be seeing? I realize you cant use the muffs to get a good water pressure reading i just wanted to make sure my hoses didnt leak before I go to the water.

[Lunkerlure]

I have been told 15lbs at full trim and woth

[Gsmith223]

am I tapped into the right spot? what is the minimum i should be seeing?

[Gsmith223]

Any help would be appreciated I am going to the lake in the morning to check it out

[Bassmeister]

No less than 18 lbs @ wot.