Pulsating when idle

If the pump is pulsating rapidly most likely valves are leaking or debris under valve keeping one or more from closing. If the pump pulsates slowly, comes up to pressure then low pressure then repeats, problem is pressure regulator /bypass. Or you could have a combination of both. Try lowering the pressure to lowest setting to see if slow pulsation stops. As parts age within pump and debris hinder operation you can no longer operate at full pressure. To make the pump last, use highest pressure as needed and everyday work using only 60 to 75 percent of capacity.

There is orobably a minor water leak on the output side of the pump. The pump is sensing a pressure drop due to the leak so it will run for short periods to maintain the pressure i the output line.

The wand (lance) is bad. I went crazy with the same problem. Replaced the wand and now it works normal.

Usually when a pressure washer is pulsating, either one or more pistions are not pumping. Quite often one of the check vavles for a cylider has broken and will not seal, which means you'v just lost one cylinder, and now you're running on two (etc) If a pressure washer is allowed to idle too long, re-circulating the water, it will get hot, and then melt the plastic container on the check valves. Go to : www. pressure-washer-parts.com You can order parts, and manuals.

Hello,


unfortunately these little units have this problem commonly, 9 times out of 10 it will be the plastic head or the plastic valve block on the unit will be cracked and leaking slightly... it builds up pressure then leaks out and tries to build up the pressure again and this just reoccurs over and over...

you can get this repaired but is normally about half the cost of a new unit, if the pressure is still okay i would probably recommend just keep using it until it proper dies...

If you do get this fixed, we have studied into this and believe the main cause of heads cracking is warm water say if your inlet hose is in the sun for a period of time this can cause the water to become quite hot or if the unit sits and water trapped inside the head assy freezes can also cause this. Hope this helps Kind Regards Brad

Pulsating is usually due to a leak. It could be the pump leaking or the hose, gun or wand leaking. Is there water coming out of these anywhere it is not meant to?

It could also be a valve is not closing properly or a seal needs replacing.

Well, first the easy bit... the pulsation is caused by the leak, because the machine can't hold pressure when the trigger is released.  The difficult bit is: what to do about it?  Unfortunately, there are several different places where the leak can occur and, even with the cover off, it's usually impossible to be sure exactly where the water's coming from.  In the repair shop where I work, we almost always replace every part that might be causing trouble without even trying to identify the exact source.  To do otherwise will rack the labour costs up so high as to render the job uneconomic.  We reckon that if you can't complete the job in 45 minutes it's not worth it.  Sad really, but such are the realities of our economics.
Anyway, unless you are a really competent handy-person, this is probably a job you won't want to tackle for yourself.  So your choice is either to live with it (and do whatever you can to limit the pulsating time - keep it working or switch it off immediately) or take it to a repair shop.  If you are in the UK, Karcher head office can direct you to a repairer, and I guess the same applies in many other countries too.
If you do want to have a go at it yourself, post another message here and I'll give you as much guidance as I can (but there will be a limit to the amount of detail I can provide, as I can't get in to writing a complete service manual!).

you have an internal crack in the out let head of the machine very comon in thease machine and not expencive to fix

you have a restriction in the nozzle end of the lance. clean with paper clip.
if not you have some dirt in the pump head valves which need cleaning