I have replaced the spill valve on my Karcher 620m pressure washer with a new one. But it is still surging/ revving and won't switch off when I release the lance trigger. I've checked for leaks etc

SOURCE: Karcher 620M not drawing water

my 620m has a problem when i press the switch on it has no pressure and the pump sounds like it is not kicking in .... plese help !!!
steve ..

SOURCE: honda pressure washer cuts out when lance trigger released.

You most likely need to set your valve clearances. If it is hard to pull over or the recoil snaps back after starting your valves need to be set for sure. This may not be the entire problem but it is a good start. Also change the spark plug, a bad plug will cause odd problems and is too cheap not to eliminate as a source. In addition check your fuel, pour a little out into a white container (I like spray paint can caps for this) and look at the color. If it is yellow to orange it is bad. You can pour it into you car, the car electronic sensors will compinsate for it quality but a small engine can't. Use a NGK BP6ES or BPR6ES plug.
You need:
Feeler gages
10mm open end wrench
14mm open end wrench
1 long shaft screw driver or rod
1 spark plug socket and ratchet

Remove the spark plug and the valve cover. Pull the recoil over slowly until the intake valve opens (intake is closes to the carb and it will go down when it opens). Now put your long screwdrive down the spark plug hole. Slow pull the engine over until the screwdriver handle is at it highest point, this is top dead center. It may take a few attempts. Now check your valve clearance between the rockers and the top of the valve. The intake should be .006 and the exhaust .008, both can be +/- .001. To adjust: hold the large nut with the 14mm then loosen the small one with the 10mm. Lefty loosey. Now turn your large nut until you get the correct setting and then tighten the small one the lock it in. It may take a few attempts and alway reverify your setting after you lock it down. Once done, find top dead center again and reverify. Now your valves are set.

SOURCE: Electric Karcher pressure washer surging when turned on

Dear firenutt681,
One simple thing you can do, is to check for leaks. Check if hose at machine is leaking. Check gun if it is leaking. You can also check if water still comes out of lance nozzel. These leaks however so small, will cause the machine to surge.
Another reason is due to a faulty SPILL VALVE. This spill valve( often called CONTROL VALVE) will contract when the gun is closed. When it contracts under the enclosed pressure it will switch off the machine by means of a Micro Switch. Now if this Spill valve is faulty it will loose its compression under pressure and puts on the micro switch again. This can be seen once in a while or more frequent, as in your case. I sometimes do service Spill Valves, but mostly I replace them with a new one. I do not know the model number of your machine, but normally you have to open the cover and you should spot the spill valve on the head. Most probably you see a thick wire or a cap containing the micro swith. If you find the micro switch, you have found the spill valve. Sometimes it is a bit hard to pull out the spill valve. Myself, in various Karcher models I remove the spill valve by trying to feed water and put on a bit the machine. In this way the spill valve will be spitted out.
Another reason which makes your machine surge, is leakage from from the detergent inlet.
If you do not see no leakages at all....then for sure it is the SPILL VALVE.
If you cannot do this job yourself or you do not find spare parts...you can continue using the machine as it is...but before closing the gun...switch off the electricity. I only recommend this in an emergency. You do this so that you do not leave the machine surging. This surge will for sure damage the electric motor and the capacitor (assuming it is single phase).
Regards,
Fulltech.

SOURCE: Karcher Pressure washer surging/pulsing

here is a troubleshooting link for Karcher products

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

SOURCE: When I switch my karcher k4.97 washer on it just

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