Operator stated he had filled up with fuel prior to launching at Stone Ramp in Caddo parish.  Drove his boat approximately three - four miles south of Stoner Ramp on Red River and stopped.  Friend with him attempted to set the fuel pressure on the inboard engine while engine was off.  Operator restarted engine.  It backfired, and didn't crank.  They smelled smoke, raised engine cover, smoke and flames erupted catching boat interior on fire.  Operator used his fire extinguisher until it emptied, then jumped into water with companions.  Several persons were operating PWC's in the area, and they were able to spray water on burning boat and put out flames.  Caddo Sheriff's Office was notified and towed the burned boat back to Stoner Ramp.  Operator, friend, and operator's young child were not injured.  All used PFD's.  No alcohol or drugs were observed by anyone.  Possible cause may have been due to equipment failure and/or unqualified maintenance.
Shreveport                    