Bissel Won't Spay Water?

I replaced the pump in my Bissel Proheat 8910 thinking that is why it was not spraying. I think I figured out what the problem is but don't know what I should check. The valve in the pump is not opening due to a lack of suction from the hose that goes to the motor. If I disconnect this hose from the motor assembly and give it a light suck the valve opens and the water begins to spray. What causes the suction in this hose? The motor fan? Could it be a seal gone bad?