Question about Karcher K2.26 Electric Power Washer

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Karcher K4.97M electric waterblaster cycling

I have a Karcher K4.97M electric waterblaster that has started behaving strangely. When it's powered on, but the trigger is not pulled, it continually cycles on and off (about a 2 second cycle - almost as if its building pressure but not holding it). With the case open, the valve that switches it off when pressure builds, is cycling up and down.
When the trigger is pulled, the pump runs continually as expected, and seems to all work fine, but the output pressure is very low.
It feels like its bleeding pressure internally somehow. I've pulled the valve assembly apart, but nothing obviously amiss (but then again, I'm still decoding exactly how it works!). Andrew

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  • 56 Answers

It sounds to me like the unloader valve is bypassing internally.

Posted on Nov 18, 2009

  • mngyler Jan 03, 2011

    Hello Karcher user world,
    I have exact same symptoms as described by andrew142 above, with my 399M electric unit, but I am not sure if it has the “unloader valve” referred to. Can someone please describe where that component is


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