Briggs and Stratton 126T02-0301-B1 motor won't idle but runs at full throttle.

Hi everyone new guy here and could really use some help. I got this power washer from my father who used it twice and put it away. It has a briggs and stratton 126T02-0301-B1 motor on it. So far I have tried changing the oil, cleaning the carb, when cleaning did not work I replaced the entire carb with an oem replacement, and when that didn't work I changed the spark plug. The washer fires right up on the first pull as long as I have the trigger pressed on the sprayer. It will run full throttle this way for as long as I keep the trigger down. Once I let go it dies. I have checked that the auto choke arm is in the right position and it does seem to be. I really would love to get this thing working but I am completely out of ideas on what to try. Any help would be appreciated!

Most likely you have an unloader valve problem in the pump that is stuck on the pressure side, and isn't working to go into bypass when the trigger is released.

Please let us know if you find out what is wrong with it. If you have tried adjusting the carb and still have the same problem ILENGINE is probably on the track. BTW, I'm new to the forum. Nice to meet you all!