Need help with pressure washer

We just bought the pressure pro 8 gpm 3000 psi this past week and I replaced the water hose intake with a 1 inch intake for a buffer tank. When sitting at idle it cavitates severely I put a 3/8 hose going back into the tank for circulation and there is a lot of pressure getting pushed through the line at idle. When we use it with the gun no problems. Working on a big job and need help please. We are running 250 ft pressure hose.

Hope these help

That looks like the K7 Unloader that tend to surge when in bypass. I only had one of those type Unloaders in the past and I replaced it. If its surging in bypass its most likely going to be the problem within the unloader.

Since its working when your squeezing the gun I would keep using it but I would also order a different unloader asap. Since its surging in bypass you should still be OK because its keeping the water circulating which is key here because if not your pump will overheat if you leave it in bypass to long.

Do you think it’s a bad unloader or will all of them do this. Thanks for the reply

The k7 I am referring to

It’s definitely the unloader. If you need one fast you can call your local rental store. That is where I got mine.

Since your pressure is fine you say when you squeeze the gun then its going to be the unloader. I think the K7’s can be rebuilt but since its brand new, why not take a video with your phone of what the problem is and then call the place you bought this setup from. That Unloader isn’t cheap(At least $90 range).

The K7’s are known to having surging problems and if I remember correctly(At least 10 yrs ago) I had a similar problem. Today we only use YU-2140 Green spring Unloaders. Very basic and they work great.

That’s the same one we have on our hot wash. I am going to call them tomorrow. Thanks

Ok so I called bill at power wash store and they explained that when I received the washer the k7 was set up for force fed with hose not tank fed. so to test it he had me pinch off the hose a little and it worked perfect. He has to send me the 7.2 instead of the 7.3 orifice to fix the problem for good. Everyone was right about the customer service at

An 8gpm machine set up for force fed?! Wow, must be a expecting you to have some awesome outdoor faucets in your area…

Sent from my Galaxy S3 Android

That’s what I was thinking

I have my eye on that exact machine, are they all set up like that? I want to make sure that it is set the way I want it before it gets to me, I don’t want to have to mess with anything and you shouldn’t have to, with a brand new machine!

You could call and ask bill at the power wash store but I remember someone saying there’s was set up already to be tank fed so I know they could do it. I knew there wouldn’t be a problem but this was my first experience with the k7 but now that it’s fixed it’s pretty sweet

If you can find them for under $3000 now you better jump on it because the prices from pressure pro have gone up around $250-$300


I use Pressure Pro and have been using there Commercial Machines for a while now. Once I started using them I never had any issues so I just kept doing business with them. I would call them and talk to one of there repair experts. They always seem like they know everything about their machines!

Is that the polychain model?

Yes it is