Tearing up pumps

Hey, I use a pressure washer to clean my dog pens. I recently ran a 1" water line out to them. It’s about a 100’ run. The problem I’m having is I’ve been tearing through pumps. I think I’m on my 4th for the year. It’s a subaru powerstroke with the electric start. I borrowed a neighbor’s (his is a commercial washer, a five star I believe) and had the same problem. So I borrowed another and the same issue. They will all start fine and then as soon as I quit washing the first pin it sounds like they load up and then I have no pressure and they all start shooting out the relief valve on the pump. I filled up a 5 gallon bucket to measure the flow rate coming out of the hose i use and it took 27 seconds from the end of the garden hose so i should have plenty of flow. Any idea what could be causing this?

How long is it running without you pulling the trigger for flow though the pump?


sounds like its you not the pump? answer the question Bluewave asked and if its longer than 2 minutes .you may be the problem…


People dont realize what an issue this can be. Hell, I didnt for a long time. My old home owner grade washers still lasted several years despite me letting them run and build heat. I know better now though and try to pass on how critical this is to the longevity of these pumps.


Less than a minute. If I let off the trigger for just a few seconds it will lose pressure

Before it started this? Did you let them run for any real amount of time without pulling the trigger? It sounds like seals., o rings, and/or possibly valve damage has occurred. Once it gets hot inside and you pulled the trigger bringing in cool water its a shock to the pump components. It make just have a thermal relief valve that needs to be replaced. Hard to say with the information provided

I’m not sure it would be the pressure relief valve since he tore up 4 pumps and his neighbors machine has the same problem.

What is your water source from? Are you using well water?

Did this problem happen after the 1" line was run? What is the line be made of?

I’m on well. It’s a 1 inch PVC line I put in right where the water comes into the house after the tank. At first I’d let it run when I didn’t know what I was doing but after the first pump I learned not to do that. I start it while holding the trigger and just keep it going. Soon as I let off the trigger for just a few seconds and go to the next pen it drops in pressure

Sounds like there is 2 consistent factors

  1. You
  2. The water supply

I doubt it is 2 because your bucket test that being said it could be a solid flow 95% of the time and cut out for 30 seconds or somthing along that line but I doubt it. Then the most common problem is option 1 of human error, it sounds like you have done your reserch and arnt making any basic mistakes. I think you should trouble shoot by switching each factor and go from easyest to hardest. 1 get a friend to run the machine for a few and see if you ether were doing somthing wrong or if he spots a problem you didnt. 2 go try a diffrent houses water supppy, I doubt it will do anything but it almost certanly cant hurt.

It could be factor 2.

I’ve seen sand like grit collected in the bottom of the water tank on a toilet bowl. Are you running any kind of filter between the well pump and your machine?

I asked if was a well because with so many bad pumps in a year it seemed like something might be killing them that was in the water.

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You say it’s dropping pressure when you let off the trigger. That just sounds like it’s going into bypass. Does the pressure not return when you pull the trigger? The issue isn’t really totally clear from what I’m reading.

@bluewave18ft, he says hes been through 4 pumps this year, then borrowed a commercial one from a neighbor and then another one. So it’s either 4+2 more or 4 total.

His title is tearing up pumps so it sounds like hes wrecking the pumps. He says they have no pressure and they blow out the relief valve. I’m not sure but isnt that a thermal valve he might be talking about?

What do you think?