For electric pressure washers this is normal operation and the motor should start up again once the trigger is engaged. If this is a gas powered pressure washer, then the pump is not going into by-pass mode and the pressure build up is overloading the engine causing it to shut down. The pump unloader controls the by-pass and will need to be repaired or replaced. for information about how to obtain a parts list. for information about how to order parts Click Here.