Abstract: A pump-priming device configured to fit within the pump inlet circuit formed in the valve body of an automatic transmission is disclosed. The present pump priming device comprises a fluid-conducting structure having a fluid inlet and a fluid outlet, which is fabricated from sheet metal or flexible tubing and is designed to be installed within the original equipment manufacture valve body as a drop-in-place component. The present pump priming device diverts the flow of automatic transmission fluid (i.e. regulator exhaust fluid) released by the pressure regulator valve, which under normal operating conditions would flow from the pressure regulator valve back to the sump, and to redirect such flow of regulator exhaust fluid back to the pump inlet. Such redirection of regulator exhaust fluid pressurizes the pump inlet circuit and raises the output of the pump to provide adequate transmission fluid flow within the hydraulic system at low engine speeds.