It absolutely will self prime. The problem in my case was due to an older production process Andair used. They test every pump with fuel and and then drain and packaged up. They didn't think the pumps would sit on the shelves/boxes for as long as they did for many of us builders. They would then begin to dry and some of the components froze up. As a result, when I would turn my on it would make a high pitch whining noise. The newer ones are now flushed and preserved with oil to protect them. Once I received one of these, I simply dropped it in the fuel line, connected it up and it self-primed just fine.