Fuel pump check valve

I have a question about the fuel pump check valve. I got a tank full of mud over the weekend (it was a VERY deep puddle) and it clogged my fuel filters so bad that the fuel pump stopped pumping gas. I have cleaned it all out and replaced the filters.

On to the question: I want to make sure that everything is clean before I put it back together. In the picture below the red box is the fuel line outlet, the purple box is the fuel pump connection, and the blue box is a pressure regulator/filter. When I blow throw the fuel pump connection with my mouth, I get very little air out of the pressure regulator and fuel line connection. I assume that it is because the required pressure for the regulator is much higher than my mouth's PSI.

Can someone confirm that I should not be able to blow freely throw the pressure regulator? I just want to make sure that it is not blocked with tons of mud and that it is operating normally.

Update for anyone who is searching. The fuel pump regulator has a spring and diaphragm in it. You should not get much air out of the fuel outlet when you blow into the fuel inlet. Completely normal.