I have a Karcher K 6.85 M pressure washer that has developed an
> apparent fault:
>
> When using the Vario Lance that came with the unit, as soon as I turn
> the pressure above 3/4 of the max, the unit starts to pulsate, i.e. it
> works in fits and starts, works fine for a few seconds, then it stops,
> and starts working fine for a few seconds again.
>
>
> It works fine if instead of the Vario Lance I use the Dirt Blaster > (rotary pencil jet)
>
> The closest reference in the Manual is:
>
> "Strong Pressure Fluctuations: Clean high-pressure nozzle: Remove dirt
> and debris from the nozzle bore, using a needle and rinse through with > water
> from the front".
>
>
> But, in my case, there was no dirt in the nozzle.
>
>
> The unit has been used little. It worked fine a few months ago.
I would check for a problem with the supply first. If the supply hose is kinked or your supply flow is poor then the pump will pulsate like this.
Tim