RedactedNarrative: On Sunday, September 10, 2017 operator told Officer that him and his wife went on a cruise of Pomona Lake.  They told Officer when they got over by the Management Park Corp of Engineer ramp the boat died.  Operator told Officer that he tried to start it but it would not start.  They told Officer that they decided to fish.  Operator told Officer he tried to start it again and heard a loud boom.  He told Officer that when turned around the top of the engine cover had blown off and the engine was on fire.  He told Officer that he tried to put it out with the fire extinguisher but it did not put the fire out.  He told Officer that they put their life jackets and jump over to another boat the came over to them.  State official explained that from his knowledge of fire accident investigations with outboard engines, it was more than likely caused by a fuel leak into the main engine compartment, causing the engine to fail, fumes to accumulate and then by trying to restart the motor, a spark caused the explosion; by lifting the cowling, air mixed causing the fire to erupt.