My electric Karcher pressure washer does not shut off.

SOURCE: Turn water on then actuate wand trigger. Pressure

You gave a very close solution yourself for the problem. But other leakages can cause such symtoms.Forexample a leaking head or a leaking chemical inlet. These can be caused because the spill valve (pressure control valve) is stuck. When this valve stucks it will leave a micro switch ON. So the machine keeps working with the gun closed. This will in turn creat internal pressure and damages the head, valves and chemical non-return and even damage outlet hose. So besides fixing the leakages you must check and service the spill valve. I often replace the spill valve. One must also checks if the micro switch is faulty. Now very important that what you mentioned that the machine cycles at one minute intervals, with trigger closed...this is most probably always the spill valve fault. If you open machine you see a place where there is a wire..this belongs to the micro switch...under you find the spill valve. Intake and suction valves may now also have a fault. Also there are systems with non-return valves at the machine outlet. You have to tackle by elimination. Fix the leakage..then tackle spill valve and micro switch.
Fulltech.

SOURCE: My Briggs and Stratton Power

Ican see im going to have to wright this whole thing again . This sight is not good for people like me who know the answers . Something always pops up and loose my well thought massage . like the one i just wrote to you . Briggs olny makes the engine on your mechine you have 3 to 4 differant other companys that make all of the other parts this makes it diffelculy for anybody to get parts for the mechine . But there can olny be two things wrong with this mechine . The first is you have a problem with the valves on the pump body . Do you see brass caps on the valve body remove them one at a time . Check the valve you can remove them with a small pair of niddle noise pilliers look at the plastic cages around the valves they tend to break and jam the valve seats it olny takes one to cause this condution you describe . The other thing it could be is the unloader valve is stuck . This is the part under the pressure control knob and you will need to remove it . What it dose is allow the presserized water to recurlicate back through the pump body when the trigger is not open . This could also cause this condution . Most of the time it can be freed up with some WD40 and most are not servicable as a unit and lots of luck trying to find one .But the chances are good you can free it . In the winter time you should put antifreeze in the mechine disconnect the plug wire pull the cord until it comes out the other side this will protect it from the water freezeing and expanding and damageing parts aswell as corroition . Well good luck from what you descriped the valves but you should also turn that pressure knob in and out on a regular baicis to keep it free