This might sound a little strange, but on my CSS The intake strainer has to be pushed in a certain way or mine won't draw air either. With the pump running, I have to play with the strainerpushing it in and tilting it some here and there. I don't know if it will help you, but for some reason the strainer has to be puttting pressure on the air intake. I can't explain it but for some reason it works for me. Sometimes it takes quite a bit of fiddling, but my air starts going eventually. Good luck!