This started happening about a year after I'd bought the unit. It works fine as long as the trigger is on, but when released the machine keeps pulsing on and off. Have cleaned inlet filter, and rep[laced water hose.
I've seen that spare parts are available, but is this a fault for a diy repair? And if so, where can it be repaired (East Surrey)

Brian Smith, March 2010

Found on mine that the high pressure housing where the small red relife valve pushes in had cracked thus allowing the water pressure in the high side of the pump back to the low side so with the gun released the unit keeps building the pressure up and instead of it then holding the pressure it bleads away again to the low side. So there is no external water leak and when the pump is running its not quite as powerfull as it was. Replaced housing cost £13.99 now back to full power no pulsating quite easy to strip down just put back the way it comes apart

phil cool, October 2010

Hi Brian,
Just having an identical problem with my K 5.55. I know its late in the year, but did you have much luck in tracing the culprit? I have my machine in pieces, but nothing looks like it is in need of replcement

Mike, August 2010

When mine did this I found that the the rubber o ring on the hose connection had split. Replacing this cured it! Hope this helps.

John Radford, April 2010