This DIY repair guide explains how to replace a pressure washer pump. The pump creates the water pressure for the spray nozzle. Air in the inlet water supply can damage the pump, as can detergent residue left in the pump. If a damaged pressure washer pump is causing low pressure at the nozzle, replace the pump with the manufacturer-approved gas pressure washer part.
This procedure shows Craftsman pressure washer pump replacement but the same basic process works for pump replacement on Briggs & Stratton, Snapper, Troybilt, Husqvarna and Generac pressure washers.