Prochem Legend chemical pump problem

The chem pump is not feeding chemical. It keeps filling with air. I have two valves coming off the truck mount; one for my solution line and another for mixing chems and rinsing stuff. When I prime the chem pump it pulls the air out and I can turn the valve that is for mixing on, and the chem flows through. But as soon as I go inside and start using the wand, it fills with air again, and I'm not getting an chem to the wand.

Also, might be unrelated but the three way valve that controls the...

Prochem Legend chemical pump problem