Troybilt 3000 PSI/2.7 GPM pressure washer with a B&S 8.75 Professional Engine starts easily IF there is no tip on the wand and the trigger is squeezed while starting. After starting it will continue to run even when the trigger is released, although it does surge a bit. Then when a pressure tip is installed and the trigger is squeezed the PW will shut off within a second or so. However, there is normal pressure coming from the tip for a brief moment. Do those symptoms indicate a bad unloader valve or something else?

I removed the unloader valve by removing a "U" clip and everything looked normal to me, i.e. no trash seen. However, the plunger was very easy to depress--maybe even less than pressing the plunger of a ballpoint pen. Also, the tiny ball valve that the plunger apparently engages did not seem to move when I pressed it with the backend of a wooden shish kabob stick (to prevent damaging the ball) and it seemed unlikely to me that the plunger could move that ball--if that's what it supposed to do.

Thank you for any help you can provide.