foam cannon + gas karcher = not working

I recently got a foam cannon from autogeek and finally got the pressure out of storage but cant seem to get it running like its suppose to and i was hoping that someone can point out the mistake im doing.

the pressure washer is a 2400psi gas karcher.

the foam cannon is the one that you can buy from autogeek (with the karcher HD attachment)

the problem is when i hook everything up and let it run for a minute or so if i push the trigger down to spray it will come out in bursts (spray hose pressure for 4 sec and then high pressure for 4 seconds then hose pressure for 4 etc...). it will do this for as long as i hold the trigger down. i thought that it was the pressure washer at first and was going to open it up to clean the un-loader valve but before i did i tried the original wand attachment and it worked flawlessly ruling that out (constant pressure as long as i held the trigger). i wanted to play around with it more so i took off all attachments (wands/tips) and it would not do a pressurized spray. correct me if im wrong but this made me think that this pressure washer needs a back pressure in order to spray out a pressurized spray. has anyone had any problems running the karcher gas pressure washers with the foam cannon? does it only work with electric pressure washer? is there any chance my foam cannon is broken/defective? any help would be great because i felt like i just bought a $120 paper weight.

 

mmm looking at a few foam guns/cannons, I believe you need to top up the foam cannon's container and also set the valve on it for how much foam produced or smfin.

 

Fixing your Karcher high pressure washer

sounds like the unloader to me. I used mobil 1 grease and its good as new