Karcher pressure washer keeps pulsing when not in use and has lost pressure when in use

My account pin on 0711825797

Just google " stripping down Karcher KB4040" A YOU TUBE CLIP will show you hiw to fix it and what tools you need

This fault is within the control head, under the detergent valve is a small spring loaded valve that acts to induce the detergent, this will have failed, the shaft of the component breaks off the disk base leaving a small hole in the centre of the disk. This is enough to allow pressure past the component. The machine will pulse when operated and will not induce the detergent. I've looked everywhere to find this part as I have a karcher with the same fault.

i fixed mine works good easy too watch my video step by step i put it on youtube

http://www.youtube.com/watch?v=8XDPDhg_acQ&list=UUiF9Qw4CmLuBqWFGanj1KIA&index=14&feature=plcp

Is liquid leaking from the base, when the Pressure washer is on ?
I have the same Problem, the leak is from the seam of the Manifold housing. There is a small crack in the seam. A manufacturing defect.. A New Manifold Complete Replacement is $61.03, about the half the price what I paid for this pressure washer at Walmart... :( If under 1 year old, and you can find a receipt,Karcher will replace the whole Pressure washer under warranty.

Is there a leak from the bottom ?
If so Problem, the leak is from the seam of the Manifold housing. There is a small crack in the seam. A design weakness.. A New Manifold Complete Replacement approx. $61.03.
If not you may replace the Pump Manifold Housing from Karcher, or locate a local Karcher Service Center.
If under 1 year old, and you can find a receipt,Karcher will replace the entire Pressure Washer under warranty.

you might have some dirt in the valve ( if the hose is shaking then check them.)

here is a troubleshooting link for Karcher products

http://www.the-power-washer-advisor.com/electric-pressure-washer-troubleshooting.html

depending on amount of use i have found failures of the piston spring and retainer which are located inside main housing of pump,these cause pulsing and no pressure,you need to remove pump head and face plate to get to them,hope this is of help

Hi the pump surges when there is a leak on it find the leak that should sort your prob.
Hope this helps. Sean