Well this getting to be common here with pressure washers being labeled with higher output pressure than actually are capable of due the pump the OEM install. I would not be surprised that a class action suit is file sometime soon about this like the one where engine were mislabeled about hp ratings.
Yesterday I received in a Dewalt DXPW4240 label as 4200 psi unit. Customer claims it blew a high pressure hose and has very little pressure when operating the wand.
Connected up new 4500 psi hose, wand, and a 6000 psi gauge. Testing show it to have a max pressure of 3600 psi while unloader operating at max pressure setting and 300 psi with the wand operating with 4.5 gpm Zero degree tip.
Well the Comet ZWD-K4042 does claim to be 4200 psi pump but this is the problem it has 3600 psi unloader and can only be upgraded to an unloader that is 4000 psi. More likely it is a 4000 psi pump with a 4.2 gpm flow rate. Anyway it is impossible to get 4200 psi with a 3600 psi unloader. At least the pump does deliver close to what it is design to do even with a failed check valve and some other are close to failing. The water seals are also worn but this is to be expected with any pump that is used heavily. As for the blown hose since I can't anything above 3600 psi all I can figure is it is a just a hose failure not related to the pump. The failed check valve does explain why it only had 300 psi operating pressure with the wand open.
I will be talking with my customer today to see if he wants me go ahead and install a new unloader so he would have an extra 400 psi of line pressure. Anyway he is having to rent an unit while I order parts (1-2 weeks out).