its kind of a dumb set up, there is a rubber line hooked up at the block, which leads to the gauge on the dash. Essentially a "mechanical device". that hose gets pinched, or clogged with dirt really easy. Once it gets pinched, or clogged with dirt, it stops working right.

If possible, take the hose off the block, and off the gauge and blow air through it. From the sounds of your other gauges, water temp especially, it sounds like you dont have an issue

+1

Last season (I bought my boat in September and have no idea when the water pump impeller was replaced) my boat showed zero pounds of water pressure at idle and about 15 pounds underway. I am having new impellers installed and hope to pick up the boat tomorrow (May29). I'll post the pressure readings with the new impeller. I've been told 1-3 #s at idle and up to 25 psi at WOT. Sounds like everyone replaces this item at the start of every season.

Worked on it tonight. The brass fitting in the block has an small orfice and sure enough it was plugged with rust. I ran a small wire up in the block and all kinds of junk started coming out with the water. You would think that much crap would have washed out over the weekend. We ran Close to 100 miles Sunday.

I'm seeing good water pressure (~25 at 4 - 4.5k RPM), but my gauge is all over the place (20 - 30). Is that normal?

Seller said the impeller was lat replaced 2 years ago. I have service scheduled, but figured I'd ask.

there isnt no thermostat . therefore not much water presure ever .. trust me mayor youre moving water . 2 stage ke water pump on that motor .. also on a side note if you decide to run a stat . youll need to add a presure releif valve . as water pressure climed above 40 lbs ... just a little note .

Rob boat runs great!!!!!!!!!
Just worried no water temp. I think an engine needs some heat to operate correctly.
Went out this afternoon after work 3 psi at 3k. Oil temp was 180 to 200 degrees. Temp guage stayed on 100. Jumped the temp sending unit to ground the guage maxed out. So i'm thinking it needs a thermostat or a restrictor plate in the thermostat housing. We used to run these in our late model stock car. It's just a disk that goes in the thermostat housing with different diameter openings. Takes some trial and error to get the temp you want.
It does have a by pass hose on the cross over tube that goes to the top of the thermostat housing. To feed the header until the thermostat opens.

watch the water pressure . teague sells the restrictors . i made my own . didnt seem to make a diffwrance .that pump moves some serious water .