On January 1, 1994, about 0659 eastern standard time, N648UA, a Boeing 767-322, operated by United Airlines Inc. as flight 984, scheduled, domestic, passenger service from Miami, Florida, to Chicago, Illinois, experienced a passenger initiated emergency evacuation on the ramp at the Miami International Airport. Visual meteorological conditions prevailed at the time and an IFR flight plan was filed. The airplane was not damaged and the airline transport-rated captain and first officer, 5 flight attendants, and 162 passengers were not injured. The flight was originating at the time of the incident. The airplane had been pushed away from the gate and the No/1 engine had been started. During the No/2 engine start, the fuel flow was reportedly high and a flame aft of the engine exhaust was observed by a passenger seated on the right side of the cabin. The passenger then shouted "fire", opened the No/2L door and deployed the slide. Passengers then began an uncommanded evacuation the airplane. The No/1 flight attendant advised the captain that passengers were evacuating and the remainder of the passengers wanted to evacuate the airplane. The captain directed that the No/1L and No/1R doors be opened and the emergency escape slides deployed for continued evacuation of the airplane. The captain secured the engines then entered the cabin and stopped the emergency evacuation of the remaining 24 people.