Iv'e Been Told The Anti Siphon Valve In My Fuel Tank Is Clogged And Needs To Be Replaced. Don't Know Where It Is Or How To Do It. Help Please.

Most time I have seen them is right on the tank with the fuel line attached to it.

My Fuel Line Attaches To A 90 Degree Fitting On The Tank Is This It?

yes, that is it!

The last one I saw was anti-siphon/hose bib all in one. When taken out there will be a ball in the middle of it.

Mine was on the top of my tank, right next to my fuel level float underneith an access panel in my floor. I doubt it is clogged but it is restrictive and your motor will start much easier without it.

Ok, Next Question. Is This Separate From The Pick Up Line Or Will I Need To Replace The Entire Piece?

Should just be a screw-on fitting

How do you know it is clogged?

I just had this same issue a couple of weeks ago. Mine was a combination anti-siphon/ hose bib screwed into the 90 degree fitting on the tank. It looked fine when I took it out, but I replaced it with an Evinrude/ Johnson factory replacement part. It's a quality brass unit, and the opening in the hose bib was a bit larger than the old aluminum one that was on my tank. Needless to say my stalling problem went away.