My Karcher 3.99m has no pressure. Garden hose pressure fine, 3/4'" hose, no kinks, cleaned filter, cleaned nozzle, motr runs, no leaks. it worked fine last year.

It sounds like there may be a potential issue with the pressure build-up mechanism in your Karcher K2 compact. The constant motor running without water pressure could indicate a problem with the pump or the pressure switch. I would recommend checking the following:

1. Check the inlet filter: Ensure that the inlet filter is clean and free from any debris or blockages. A clogged filter can restrict water flow and affect pressure.

2. Inspect the nozzle: Make sure the nozzle is not obstructed or damaged. A blocked or damaged nozzle can restrict water flow and affect pressure as well.

3. Check the pressure switch: The pressure switch is responsible for regulating the motor and water flow. It's possible that the switch is faulty or not functioning correctly. Consider contacting Karcher customer support or a professional technician for assistance with checking and possibly replacing the pressure switch.

4. Examine the pump: There might be an issue with the pump itself. It could be worn out, clogged, or experiencing other internal problems. In such cases, it's best to reach out to Karcher customer support or a professional technician for further diagnosis and repair.

Remember to always follow safety precautions and consult the user manual provided by Karcher for specific troubleshooting steps and guidelines.

blockage in the wand nozzle jet

Take the wand hose off the washer itself and you will likely find a filter outfit that gets plugged up. Take it out and clean it real good. Mine was full of stuff out of the hose that gets in when the hose lays on the ground and stuff gets in. Also if hose has been used to drain anything. My filter was plugged and with the pressure it created the washer would not shut off. There could be a filter in the wand area in some models.

what you describe indicates a problem hose or block nozzle jet
if it doesn't play up with a normal nozzle then it is not the hose or jet but that particular wand and nozzle you are using
do you have a sufficient inlet water supply for the pump

Make sure that while you are running your pressure washer, other machines that pull

large volumes of water like a dishwasher or washing machine are not running. check and make sure

the hose you have tied to the pressure washer is not collapsing or has any kinks in it.

check the filter where your water hose ties in to your pressure washer, make sure it

is clean and does not have any debris or hardwater buildup, clean the tip at the tip of

the wand. if it is reduced in size by hardwater buildup, will not work properly, good luck!

that is sure signal of insufficient water supply!

try easy solution first:
make sure that your mains is fully open, that tap on whihc hose is hook up is fully open and hose is of "decent" diameter to allow sufficient flow.

if above solution do not work then you need to make another, more difficult arrangement:
prepare 20litres pressure tank with inlet connected to mains and outlet by short hose to power washer, fill it with water from mains, keep it under mains pressure and use karcher power washer normaly. this will solve water supply problem. twenty litres will last about 2min, because it is re-filled, under standard pressure therefore it will last about 3min...

third possibility is to stop washing...

if you find my advice helpfull, please do not hesitate to left the comment and vote for me, thanx!

The inlet screen orientation is of no consequence. Either way should work fine. Check two things...

1) Many of the spray nozzles have a high and low setting at the tip of the wand (where the water comes out). See if your nozzle has any "Push-Pull" movement (with the unit turned off). If so, it might be set in the "LOW" setting and needs to be changed.

2) Located on some SIDE MOUNTED pumps is a "Variable-Volume" adjustment. It may need to be turned to increase the flow and should be marked with a plus (+) and minus (-) along with direction arrow.
NOTE: If your pump is mounted on the bottom of your engine you will not have this adjustment.
Hope this helps!

Brother Art,

Try this trick; it always works for me. Assemble the garden hose to the washer, install the HP hose, turn on the water. Now, make sure that there is no air trapped in the garden hose. Manipulate so as to direct any air trapped in the line to the washer. Connect the gun and continue to allow water to "free flow" for several minutes. Now, work the trigger, allowing the unit to rise to "house pressure, and then pull the trigger, dropping the pressure suddenly. This displaces any air hidden in the system. Do this several times, and start the washer up. If this doesn't get you up to pressure, repeat the above on an abbreviated scale, and hold the trigger on the gun down while you start the washer. This should do it.
Regards, --W/D--

when at rest can you hear your machine start then stop every 1 or 2 seconds?

I have the same problem with a Karcher 2400hh.
Go to: http://www.wmpcs.com/index.php?main_page=page&id=14
they have the best diagrams and answerss that I have found.