We switched to a K7.3 on our 3500 psi 8gpm water dragon.

I have 1/4" hose barb to the water tank for the bypass. At this time the feed line is the old 3/8" ID that came with the machine when it had the spring valve on it.

It settled down a lot, but now I cannot feather the wand like I could with a spring bypass valve. I do like not having my arm ripped out of my shoulder, but if that is characteristic of K7, then we will have to go back to the other style so we can feather with our high pressure valve at the wand end. I was able to virtually trickle the spring bypass, but the K7 requires a lot of opening on the valve so it does not help with slowing the flow enough. 

I had #9 nozzles, 15 and 25  (green and white) and two things were not cool.  The pattern on the white was very inconsistent compared to the small white nozzle we used when I could not control the #9 nozzle. that other tip i get a beautiful consistent wide fan pattern that cleans very fast.

When on the gun we are reading 3K psi on the gauge installed right before the pressure washer hose is linked up.

Tomorrow I am going to switch the 3/8" ID line down to a 1/4" ID and see if that will help

While waiting for an answer I will be out flying on the pressure washer wand since I cannot keep it on the ground with the new K7 installed...

Pretty confident it is operator error...

1/4" by-pass line? That is way too small for 8 GPM.   If the unloader has a 1/4"female fitting ,..you should be using the largest barb available with 1/4" threads,.....You can go much larger on by-pass,..1/2" 5/8" or even 3/4".   I suspect you are calling the feed line the hose that goes from the pump to the inlet of the unloader,..3/8" shouldn't be an issue there.  

I've always heard the K7's are fussy? I use the Giant Orange spring unloader,..trapped pressure type,..and I like it better than any I've ever used. They use compression washers instead of a spring. Very smooth operation. 

https://www.kleen-ritecorp.com/p-1963-giant-adjustable-unloader-3000-psi-13-gpm-orange-springs.aspx

Jeff

Andy the pressure washer is fed with a 1" line from the bulk tank bottom bulkhead.

the line in question is the bypass line out of the back of the K7 for the bypass line back to the bulk tank at the top.

The purpose is to bypass the water when we are off the trigger. I have been told a 1/4" line will cause enough back pressure so it will not cycle rapidly.

However, if the K7 style unloader will not let me dial back my water flow at the wand end so we can adjust our flow rate and pressure while doing edges inside step corners etc etc, then I am going to abandon the K7 concept.

Jeff
With my old spring unloader I could feather the stream back at the wand at will and that way I did not have to wear muddy water along the edges of concrete etc. I have a high pressure shut off right before the wand so I can dial in any pressure I want or wide open

Is that possible with the giant unloader you are using?

Yea Steve,.they are the same model number 22913,...Other places online also sell it for way less than the vendors who float around the boards.

Kleenrite.com you will get Pa sales tax and also shipping will be charged. Good service with them though. 

Try here also,..http://www.kimsupply.com/Products/Unloader-Valves_2/22913-Unloader-3-500-PSI-Orange     With shipping should be around $110.00  This is where I bought mine and they ship fairly quickly if I remember right. 

Also,..here is a link to a conversation about the Giant  unloader.

 http://www.propowerwash.com/board/upload/showthread.php?31595-Unloader-Confusion!

Jeff

I had some issues when the K-7 was installed. I went down to a 3/8" return, then had to change the tips on the surface cleaners upping the orifice by .5 on each nozzle. Getting those things right seemed to take care of everything.