Surging Pump


Hi all I’m fairly new to the game and I’m having what I’ve diagnosed as a pump issue. I’m running a 3800 psi 3.5 gpm Dewalt pressure washer with a factory pump, and without a gun attached the water pulsates out like a machine gun as if there were lots of air in the hose. With a gun you get the same pulsating with the pressure. Running the hose for a while doesn’t seem to clear up the issue. I’ve run the same hoses into a second smaller pressure washer and the water comes out perfectly and there’s no pressure fluctuation. I’ve replaced the filter and checked for debris in the hose connections. I checked the unloader spring and it was fine, and then I checked the check valves and found this:

The valve on the ground came from the outlet, and doesn’t look anything like what I’ve seen in the many repair videos I’ve looked at. The inlet valves don’t have any check valves at at all. Is this normal? Is my problem elsewhere? I’ll take it to a shop if I need to but I’d like to try and learn about performing maintenance on my own equipment. Thanks all.


As a new user I can only put one image per post so here’s the (empty??) inlet valve:


I can’t speak as to what your problem may be, but I do believe that AAA pumps are pretty low quality from what I’ve read. I have one on my dewalt unit as well lol. Luckily no issues at this point.


Did you check to make sure there are no cracks in the plastic cages of the check valves?