RedactedNarrative: Operator was having engine problems a passing vessel stopped to see if he needed help.  The good Samaritan noticed his engine had stalled out and it may have been caused that the operator failed to disengage the choke from the outboard.  He advised the operator to close the choke and attempt to restart the engine.  Operator completed this but did not realize he had left the hand throttle wide open.  He pulled the start cord for the motor and the engine instantly started with the throttle wide open causing operator and his dog to be violently ejected from the vessel.  Operator was not wearing a pfd and he failed to have a shutoff lanyard to his person.  The vessel was unmanned and operating at a full power in a dangerous motion in the creek.  The dog swam over to the good sanitarian who was able to retrieve the dog with the water.  The operator was now standing in chest high water when the vessel struck the operator.  The stern and prop struck the operator  and began to pull him underwater.  The vessel had now stopped running.  Good samaritian went over and was able to locate and retrieve operator.  The good samariitan was a former EMT and was able to render immediate first aid.  The t-shirt the operator was wearing was the reason the prop slowed and finally stopped as it got shredded and tangled in the prop.