What is the source of the new pump? Did you purchase it from a Chevrolet dealership? The pump could be definitely a problem.
What was the purpose of replacing the pump? Was there no power steering operation before you replaced the pump? Or was it leaking?
RepairPal Certified shops can diagnose and repair your 2000 Chevrolet K2500. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.