WaterPump problem

So ive been reading through a few water pump problems and most peoples seem to be in the impeller/hoses

I think Ive found something new.....
Lemme start with I have a 2001 210 air nautique.

I started having trouble with the engine cooling last year and went through a couple impellers..

This year I replace the impellar and wasnt getting any suction.
I started taking apart the water cooling system and tried to pinpoint the problem step by step.
I got down to where I can hook up a water hose(from the house) to the water filter and the boat will pull water just fine like this, in fact revving the engine up will suck the hose from the hose almost closed. I think this eliminates everything from the water filter through the engine and out. Right?

So now im thinking its between the water filter and the valve that comes from the bottom of the boat.
I took off the hose connecting the valve at the bottom of the boat to the water filter and poured water from inside the boat into the valve. Comes out fast and clean.
Now if I hook up a 'fake-a-lake' to the bottom of the boat with the valve open NO WATER comes up through the elbow. Shouldnt water be able to run freely though this when the valve is open?
Has anyone heard of water being able to run only one way (the wrong way) through this valve?

I'm not a certified mechanic or anything so if there is any more info anyone that can help me needs please let me know. Im at the point that I think i need to take that brass valve piece off (bottom of the boat) but this look like a HUGE pain because of the spot its in.

Any suggestions?
Thanks!

Thanks!
So I guess I will try taking the valve completely out tonight. Updates tomorrow I hope

Hey Thanks!
A little update-
Took out the valve last night and there was a glob of gunk in there, cleaned it out and replaced it so now water actually runs through it!

But. That didn't fix it, still wont suck water from there. I'm thinking at this point I may have blown out the impeller so I need to take that off again and look tonight. Problem is if i take a hose to the line leading into the impeller it will still take water but it acts funny. It doesnt have continuous suction based on how much I'm revving it up. Also it feels like the port side is cooler than the starboard on the manifolds. Will see what the impeller looks like tonight.

I talked to someone else and they informed me that the water pump on this boat was recalled at some point? Im talking to pcm today and see what they say. Its an Excalibur 330.

You are most likely are sucking air someplace.

Yes, take a close look at the impeller again. If ever run dry, it doesn't take long to trash one.