As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON ENGINE START ATTEMPT THERE WAS A MAJOR ENGINE FIRE. IT IS BELIEVED THAT THE CARBURETOR SPEWED OUT FUEL BECAUSE THE FUEL VAPORIZATION IN THE FUEL LINES OVERPOWERED THE FLOAT VALVE AND SEAT. THIS CAUSED THE CARBURETOR TO FLOOD THE ENGINE COMPARTMENT. THE SOURCE OF THE SPARK THAT IGNITED THE FUEL IS UNKNOWN.