I took the pump back and the store tested it. It did the same thing for them that it does for me (starts after blowing into the venturi line). I was then told that it can take two to four weeks for these pumps to "break in." They were willing to swap my pump for a new one, but they claimed all Octopus pumps do this. I'm curious about the break in period, so I kept my original pump. We'll see if it "breaks in" or not.