I don't think it is a pump problem. Is the fluid level above the return port in the reservoir?
If you want to change the pump, I would buy this one from Jones.
http://www.jonesracingproducts.com/ps.html#psalr
The reservoir is larger and stronger than a stock plastic one and has two pipe thread ports for the return, one on the side and one on the bottom, to make plumbing easier. It fits fine on a front runner.