A downhole pumping system in production tubing having a seal between the intake and discharge of a through tubing downhole pump that automatically deploys when the pump initiates operation. The seal automatically disengages when the pump suspends operating and redeploys when the pump starts operating again. The pumping system can be set at a different depth before restarting the pump. The seal can include a bladder like member that has an opening facing towards the pump discharge, so that discharged fluid expands the bladder radially outward into sealing contact with the tubing.