Confused Australian - help please - K7 issue?

Dear Professionals,

I have a 13hp GX390 motor, 4gpm pump with a K7 unloader, i plumbed in the bypass.

When I pull the trigger I get pressure forever. If I pull the trigger a second time no pressure.

To resolve I must take the tip of pull the trigger, then place tip, pull the trigger.

I suspect the K7 unloader could be the culprit, perhaps staying in bypass? I was thinking to restrict the flow out of the K7?

Much appreciated,

P.S I have spent hundreds of hours gleaning amazing information from this community, however only now created an account.

Wow, you’ve got a lot going on with that pump.

Do you have a buffer tank?

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No buffer tank, we have great tap pressure here. Customer water is standard & accepted practice here

I don’t want to get too far off topic but a buffer tank serves more purpose than just supplying water. It’s also common practice in the States to hook up to the customer’s water supply. Buffer tanks aren’t used to haul water to the job site. The best part about a buffer tank is that you don’t have to be on the gun the whole time the washer is running. You can set the gun down, go take care of other tasks, and not have to worry about your pump overheating. If you need to run back to the truck to grab something or, the customer comes out and starts talking, you don’t have to worry about squeezing the gun every 30 seconds. It makes working so much easier. Everyone here would highly recommend one. You’ll thank us later.

As far as the unloader did you set it properly?

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@marinegrunt I don’t want to get too far off topic either but I bypass back to my pump and it’s impossible for my seals to ever get hot with the use of one simple lil valve. :stuck_out_tongue_winking_eye:


Weirdo upstreamer. :joy::rofl:

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Haha…but you don’t share all of your secrets. Us peons have to resort to buffer tanks. One of these days I need to head southwest and hijack one of your rigs and backwards engineer everything. Then again, I’d probably need to hire an actual engineer or rocket scientist to do that. Be sure to leave your dog shampoo injector thingamajig on the truck before I take it. I want one of those too.


Thank you for this information. I will look into it. Unloader was set when I got the machine (second hand). I am using twice the hose the previous owner used. Should I adjust? Thanks again

Those k7 unloaders are finicky, have y’all read on envirospec site in the setup various types of unloaders?

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That would be the first thing I would try.

Completly lost here.
But i would mount the k7 on an unloader block and bypass to buffer tank.
My best guess for the lack of preddure is that k7 arent made for the bypass to go back to the pump.
Besides it should go back to the feeding intake not a new intake … if that makes sense

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@marinegrunt You don’t need my “secrets”. My rigs are really only beneficial in high production fleet washing. I have been thinking of selling my oldest truck with it’s equipment and I knew I’d need to just disconnect all my gadgets from it because not if but when it needs servicing nobody is going to want to mess with it? And besides I can’t have them calling me thinking they bought a life long service warranty with it. It’s just not worth it to anybody else but us lol as far as the dog washer is concerned I’ll need to test it out on you to make sure it’s still operating correctly before I send it home with you. How’s 3am work for you? :kissing_heart:

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Maybe you should start building rigs, selling them around the country, and than selling a maintenance warranty to go along with it. I bet that would be loads of fun.

I’m positive that @Sasquatch could benefit from the doggie wash. :shushing_face:

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So first thing you should do is take all that apart and re tape it you got way to much tape on the threads if you have that much outside you very well may have some blocking water flow. I learned that lesson the hard way. Have you had this problem since you got machine? Did you change anything. Different tips. Kinda sounds like you are vapor locking the pump

LOL this was my first thought. I was thinking dang how much crap can we bolt and thread onto a pump before it’s just overkill?

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I’m not digging that. Looks like it is fighting itself for water. Turn it around possibly .

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No! The Aussie’s have to do things backwards because they’re down undah. If he turns it around his toilet won’t flush. Something about gravity and the Earth’s rotation idk



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