My Karcher K5000G was working perfectly today but then it began to be slow reingaging the pump when I pressed the wand trigger. Then it stopped engaging completely. The motor runs fine but the pump doesn't engage. What could cause that and how can I fix it? Thanks for any help!!! Moxy

Maybe press regulator was reset before the unloaded was installed and needs to be set at lowest and then increased as needed.

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

Your pressure washer is either not fitted with a run/stop device in which case like mine you have to switch off within a few seconds of closing the trigger. Check your model features?
The humming noise is the motor stalled out against the pump because there is nowhere for the water to go. The shutoff is caused by the safety overload switching off after overheat.
Or, it has a pressure operated run/stop which is not working. Because water and electricity don't mix, I would suggest getting more specific help. You can download Karcher manuals /spares lists online from Karcher specialists but remember electricity is the silent killer.

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.

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

The wands that it will not run with would most likley have a little dirt in the tip of the nozzle. This would not allow the water to flow through in turn activating the pressure switch and shutting the machine down

Troy

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

To determine if your problem is due to an easily replaceable part, follow these steps:

1. Connect the water supply hose, the pressure hose, and the wand WITHOUT any nozzle tip.

2. Turn on the water supply, and press the trigger until water is smoothly running out of the nozzle
after any air is all purged out. Release the nozzle trigger.

3. Start the engine, and let it warm up for about 30 seconds.

4. With the engine running smoothly, press the nozzle trigger. The water should flow out of the nozzle (without the tip installed) at a faster rate, while the engine noticeably loads down as it used to do before your "no pressure" problem. If it does not load down, turn it OFF, and disconnect everything, and contact a Karcher repair facility.

5. If the engine does load down, release the trigger, and install one of the nozzle tips (not the black one).

6. Press the trigger, and the engine should load down, and you should have normal pressure from the wand. After you release the trigger and press it again, you will probably again have no pressure, and the engine will not load down. Removing the nozzle tip, pressing & releasing the trigger, and re-installing the tip should give you normal pressure again, but releasing the trigger will cause no pressure until you again remove the tip, press the trigger, and re-install the tip.

This is caused by a bad UNLOADER VALVE, which is located under a black cap with a metal button on it located on the top front of the pump. I don't know if you can purchase the replaceable parts from a Karcher repair shop, but when a neighbor & I took his washer to a repair place, it looked pretty simple to do this repair, and he was charged about $60 to replace a $5 (maybe) part, and it took about 5 minutes.

To determine if your problem is due to an easily replaceable part, follow these steps:

1. Connect the water supply hose, the pressure hose, and the wand WITHOUT any nozzle tip.

2. Turn on the water supply, and press the trigger until water is smoothly running out of the nozzle
after any air is all purged out. Release the nozzle trigger.

3. Start the engine, and let it warm up for about 30 seconds.

4. With the engine running smoothly, press the nozzle trigger. The water should flow out of the nozzle (without the tip installed) at a faster rate, while the engine noticeably loads down as it used to do before your "no pressure" problem. If it does not load down, turn it OFF, and disconnect everything, and contact a Karcher repair facility.

5. If the engine does load down, release the trigger, and install one of the nozzle tips (not the black one).

6. Press the trigger, and the engine should load down, and you should have normal pressure from the wand. After you release the trigger and press it again, you will probably again have no pressure, and the engine will not load down. Removing the nozzle tip, pressing & releasing the trigger, and re-installing the tip should give you normal pressure again, but releasing the trigger will cause no pressure until you again remove the tip, press the trigger, and re-install the tip.

This is caused by a bad UNLOADER VALVE, which is located under a black cap with a metal button on it located on the top front of the pump. I don't know if you can purchase the replaceable parts from a Karcher repair shop, but when a neighbor & I took his washer to a repair place, it looked pretty simple to do this repair, and he was charged about $60 to replace about a $5 (maybe) part, and it took about 5 minutes.