I am having a surging problem after replacing factory unloader with with a K7 unloader. Machine surges when I let off of the trigger and the machine goes into bypass mode. The machine is an 8 3,500 belt driven with 275 gal buffer tank. I’ve attached a video link for reference. Any clues what could be the issue? Thanks
Have you set it up? The unloader?
No. Everything that I’ve read about buying the correct sized unloader is that you don’t have to “set them up” they are “plug and play”.
Nope. Definitely not.
The K1, K7 etc are all for different flow rates etc.
The pressure can’t be set for “all” machines. Needs to be set up.
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They’re not. I just went through the same thing.
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I will do it tomorrow. Thank you!
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You can research it here, but it’s usually an issue with there not being enough back-pressure in the bypass. Test it by kinking your bypass line. If it stops jumping like that, it either needs a smaller orofice, or you need to run a 1/4” bypass line.
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Your bypass port should be one size smaller than pressure port. If not, do as as @fhpressurewashing suggested above and run 1/4" bypass hose.
I ended up having to reduce my k7 orifice size to a 3(I think). I had this exact same problem. Apparently it’s somewhat common.
I kinked the hose as Thomas suggested and it solved the problem. My bypass orifice is stamped #3 so I re-plumbed the bypass with a 1/4" hose. My question now is, will the 1/4" hose allow enough water to go through the pump to keep it cool when Mrs. Smith comes out to tell you how to do your job and you aren’t on the trigger?
This answered one of my questions before I even asked it. Thanks to all that contributed.
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Did the 1/4” bypass hose fix your problem? I am having the same issue with surging. My bypass line (currently 1/2”) and my pressure hose jump every few seconds when I’m off the trigger. New 8gpm machine with a K7 and it has me scratching my head. Seems worse at certain times than others. I thought I remembered @Harold having this problem but couldn’t find the post that I thought you posted about it.
Nothing fixed it except changing the k7 orifice. Still can’t figure out why but that did the trick. I got the orifice at no charge from the vendor I purchased the skid from.
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250 feet of hose on my 8gpm I had to step all the way down to a size 1 orifice. Even the size 2 orifice didn’t do the trick for me.
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