Air pump system

Need an explanation of how the air pump system works... or should work that is. Just installed weber, ran manifold vacumn to air pump system control valve. Seems I'm getting exaust to the air pump and it's blowing the fitting out of the back of the air pump from time to time. I'm assuming that the pump should only be feeding air and not be getting pressure from the exaust. Is there a check valve that's bad or could it be that the problem is that I ran constant vac to the valve? What happens if I just dissconnect the vac line to the control valve but leave all else intact?
Mike B.

I suppose no one knows how it is supposed to work? I figured out that the thing at the top of the tubes that are in the manifold is a check valve and that the DS one is bad.... still waiting to hear about the vacumn source for the control valve though.
Mike B.