Craftsman gas powered pressure washer kills motor when you release wand trigger.

Have you tried servicing the motor. Fresh air filter, new fuel filter and a fresh spark plug? That will help narrow down what the problem could be.

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.

I think you have one of two things going on hear, an overpressure problem or a carburetor issue with the engine.

you have a faulty presure relief valve. it is building up presure and killing the engine.

Pressure washer when you first try to start them that stop underload. We had the same type of problem with 11 hp Honda if you hold the trigger open the motor will be under less load we found by running the motor for about a minute it would work normally. Remember to make sure the water hose is turned on pull the trigger on, until water is coming out of the wand , now try and start the motor but also hold the trigger open, now you will not be building maximum pressure, after about a minute release the trigger and see if it keeps running.

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

I am afraid that is how they work even electric ones wont start unless you squeeze the trigger ,once they are running you should be ablr to release the trigger , and then squeeze it again whilst running . if yours dies when you release the trgger while motor is running -----good chance you are working at too high pressure. but to start you have to release all the internal pressure

check filter in wand and clean out nozzle hole for starters

Re-kit the unloader.

common for not starting unless trigger engaged as you are turning the pump as well as engine creating pressure,as for stalling pump has unloader valve which is probably in need of grease(use good silicone grease)this allows water to ciculate when trigger released.