If memory served me correctly, Pontiac fuel pumps have an arm on them that is pumped like a handle up and down by the eccentric. If the suggestions about prime and all are not the solution, then evidently for some reason the arm is not being pumped by the cam.

I would go back to the cam and make sure the eccentric is contacting the arm properly, and verify that it is actually moving the arm up and down. I have had situations in the past where I thought I had slipped the pump in straight, but actually had the arm on the wrong side of the eccentric. Won't pump that way.

Don