Karcher pressure washer trigger problem

If you are unable to shut off the pressure from the wand, there may be an issue with the unloader valve that is stopping it from switching into bypass mode when the trigger wand is released. The unloader valve is designed to respond to the spike in pressure created when the trigger wand is released, and to divert the flow of water coming from the pump to bypass the pressure hose and flow back into the intake end of the pump. If the unloader valve fails to switch into bypass mode, water may continue to flow out of the trigger wand. This may also cause damage to the wand. If you are unable to shut off the pressure from your power washer, stop the engine and discontinue use immediately. The unloader valve should be removed and possibly replaced if found to be malfunctioning. The inability to stop the flow of high-pressure water from the wand can be dangerous and should be fixed before continuing to use the machine.

no inlet pressure regulator as they work of mains pressure
the only pressure regulator ther eis works off the wand trigger
when the trigger is pulled the pressure in the line drops off and the regulator switches on the motor to produce high pressure
when the trigger is let off the regulator reads the pressure and shuts off the pump;or allows the pressure to by pass back to the inlet side of the pump

If you have a Karcher then you should always post your machines barcode.

full article on nozzles :
http://repairshed.blogspot.com/2013/09/pressure-washer-lance-nozzles-what-you.html

The spill valve operates at approx 20% higher than specified pressure washer operating pressure. If you have any lance issues then the pressure could be running higher than specified (machine running at same pressure as spill valve operation pressure)

your machine produces a fixed flowrate of water (maybe 8 litres per minute) and your nozzle is a fixed size. the diameter of the nozzle determines the back pressure. A piece of debris could further close your nozzle orifice and increase the back pressure. Using a new lance that has the wrong nozzle fitted can also cause this issue.

The karcher barcode is on a silver sticker and is usually 15 digits long. Example 156987400000123 is actually model 1.569-874.0 and serial number 00123....

it sounds like a flow switch that is installed in the inlet of pump can get stuck at times if you have a soap nozzle select it usually more flow moves the flow switch try and clean the flow switch if possible.

this can be that you need to bleed the system of air or that there is a problem with your trigger gun sticking when you release the trigger.
These are two things I would check before you go into the machine.

spill valve is stuck and needs to be cleaned and greased common problem....also check all connections for blockage in line

hi,
there is a small ball bearing inside the nozzle on the end of the lance , this can get jammed or missaligned and the nozzle orifice can get blocked , clean this or replace the whole lance with another 200 Bar lance .

hope this helps

Hello awcockerill:
This sounds like the bypass (unloader) valve is sticking. Here is a diagram of your machine's pump. On page 2.4 see part #1. The top of this assembly is a black plastic cover. Remove all of assembly # 1 carefully. Under that is part #8. This is the bypass valve. You need to pull this out, check that the o-rings are not bent, worn or damaged, then lube it good with a VERY VERY good waterproof grease. Re-assemble it and all should be well. The part numbers are on the diagram but where to get them depends on were you live. Karcher web site may give you a number to call. Good luck.

Sounds like the pressure valve is broken thats why you cant depress the trigger , the valve is on the pump , i would suggest taking it to a repair shop as they are fiddly things to fix