PRESSURE WASHER PUMP - Plumbed - CAT 67DX39G1I 3.9 GPM 4000PSI *PARTS/REBUILD*. Will put out full pressure for a few seconds after the engine is started and then loose pressure, took the pump apart and believe that the unloader is bad, my customer chose to go with a new pump. Oil will be drained before shipping, please contact me with any questions before bidding.