Leaks from within when operated (not from hose connections).

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.

Hi Cliff:
My experience is that the pump pressures prevent the engine from starting, so we hold the trigger while starting.
My brother has cut a wedge of wood that he uses to jam the trigger open to bypass the problem. It can get a bit wild if the wand is not secured when the unit is started..

When water is running through system, the motor has to run to keep the pressure built up. So, if the water is leaking out, the motor think it needs to keep running to keep the pressure built up. The leak needs to be fixed to the motor will not run constantly.

Leaking under trigger could be the ball seal part # 875645 if leak starts as soon as you connect the air hose. If no air leaks when you connect hose but begins to leak when you depress the trigger then replace the oring on the plunger which is part # 874820. If air leaks when you connect the hose and the ball mentioned above is good then most likely is leaking from oring # 876161 installed on cylinder plate (remove head and pull out the plate). Good luck.

if your machine was factory fitted with 'total stop system' TSS and has always stopped in the past then it is an issue with many possible parts !

does the machinw still operate at full pressure ?
if the machine can produce full pressure then it only has to produce 20 % more to actuate the TSS piston. When the stop piston moves it presses against an electrical switch tjat breaks the circuit. Producing 20% more pressure requires that your machine has no water leaks in the pump, hose, trigger gun or lance. Once you release the trigger the path back from the trigger to the pump TSS piston must be fully sealed.....

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

If the washer is the kind that shuts off completely when the pistol grip is released, the problem is likely the little pressure sensor located near the output fitting (the threaded part to which the hose connects). The sensor is a little plunger held down against an opening in the side of the pipe by a spring when there is low or no pressure in the output pipe, as when the trigger is pulled and the pressurized water in the hose is released by pulling the trigger. That completes the electrical circuit and the washer is on and continues pumping water. When the trigger is released, water in the hose and output pipe jams up super high pressure, forcing tjhe little plunger out against the spring, and the electrical circuit is broken. If you take the case apart, you will see wires coming from that area. The fix (if this is the problem) is to free up the little plunger.

It is probably air locked....Here's what you need to do. Connect the garden hose, and HP hose, but not the gun. Turn on the water, and let it run while you make sure that there are no high points in the garden hose that can trap air....Work the hose so that any air is displaced through the pressure washer. Continue in this manner through the HP hose. Shut off the water and connect the gun. Turn the hose back on, and operate the gun for several minutes, pulling the trigger and releasing. This alternately allows the water pressure to build up on house pressure and then to depressure, pulling residual air from the system. Release the trigger, and start the machine. Usually, this is enough to get full washing pressure. If it is very difficult to start, you can hold the trigger down on the gun and pull the start cord at the same time. Holding the trigger down acts as an unloader, making the starting easier.
Hope that this helps, --W/D-- please feel free to rate this solution! Thanx!

check filter in wand and clean out nozzle hole for starters

the problem may be the oil. if the oil is fine then try crimping your hose to let less water pressure through. if that still does not work lowes or home depot will fix the problem cheap. thank you for using fixya