A tool for retaining an activator ring of a hanger within a wellhead assembly during a fluid pumping process includes an annular fluid pumping sub body having an end selectively coupled with a supply of fluids and a distal end selectively coupled with the hanger. An outer ring assembly circumscribes and rotates relative to the fluid pumping sub body. A retainer ring circumscribes the fluid pumping sub body and selectively abuts the activator ring. A plurality of biasing assemblies that are selectively compressible are located between the outer ring assembly and the retainer ring, so that when the fluid pumping sub body is coupled with the hanger, an axial lockdown force is maintained on the activator ring by the biasing assemblies during the fluid pumping process.