Karcher 2500ph pressure washer spill valve has been replaced pull wand trigger pressure good for 3 or 4 seconds drops off for a second or 2 goes back to good pressure for 3 or 4 seconds drops off again for a second or 2 comes back again . does this contiually for as long as you hold the wand trigger. if you releae the trigger and start again does the same thing again. i spoke with a man who works on pressure washer and he said this is a common problem on karcher pressure washer and the problem is internal in the pump.he said replace the pump or use it as is.

SOURCE: karcher 520m spill valve jammed

Clean the spill valve!

SOURCE: karcher k2400hh pressure washer, water pressure cuts out.

Hello cikanek:

Try this:

From your posting, I assume you have removed the splash cap and the nylon bypass valve cover. Connect the water supply to the pump and connect the high pressure hose and wand to the pump outlet. Wad up a small towel and place it over the bypass valve opening to catch the valve insert when it pops out. With the engine throttle closed, pull the starter cord several times to see it the valve insert will pop out. If it doesn't come out after two or three pulls, set the throttle to low and start the engine. I have performed this procedure a number of times and the valve insert always pops out. There is no real danger of the valve parts getting seriously airborn since the actual pump output volume is very low (2.5 Gal/min).

Good luck,
Ed

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.