RedactedNarrative: Operator and Passenger #1 left dock at owners address on north side of Lake WI and went to Fritz's On The Lake to get gas.  They filled up the boat and then went to Whalen's Grade to pick up Passenger #2.  They picked her up and started back to the owners address when they got a call from a 3rd friend.  They slowed the boat and the boat engine started running rough and quit.  They finished their phone conversation and told the 3rd friend just to drive to the owners address as they were not sure if the engine would start again.  The operator went back and squeezed the primer bulb several times and then returned to the operator position and started the motor.  There was an immediate explosion from the engine and then flames started shooting from the back of the boat.  All 3 on board grabbed lifejackets and their phones and jumped into the lake and swam away from the boat.  A nearby fishing boat picked up all 3 and then they called 911.