[mr48chev]

I rebuilt a lot of those pumps when I worked in a Pontiac dealership in the 70's and there really is't much to them or much to go wrong.

They have what is known as a ring, rotor and vanes and the vanes fit in slots in the rotor and act as wipers on the inside of the ring that is shaped so that the fluid is pushed from the inlet inside the reservoir to the hose . I had to borrow this off the net and creds to the folks who have the photo in their add.

You can see the vanes in the slots in the rotor and can visualize how they should slide out to the inner surface of the ring as the rotor turns When they get to the tight clearance spots the fluid is pushed though a port that leads to the pressure hose. What I am thinking is that those vanes may be sticking a bit due to the pump sitting on the shelf for an extended time or due to what ever they are coated with gumming up. They should free up when driving a bit.

I have to reiterate again that those pumps really want high quality power steering fluid and ATF while it functions doesn't work well for smooth operation or having a quiet pump.