As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE HAD FIRE DURING START-UP. FUEL FROM PRIMER NOZZLES RAN DOWN FLOW DIVIDER ABOVE CARBURETOR INTO CARBURETOR THROAT AND THEN INTO CARBURETOR HEAT BOX AND OUT CARBURETOR HEAT DRAIN HOLE INTO COWLING. AFTER START, BACKFIRE IGNITED FUEL. NOTE: EARLIER STYLE 182Q WITH PRIMER SYSTEM AND DISTRIBUTION SPIDER INJECT FUEL DIRECTLY INTO CYLINDERS AVOIDING FUEL DRAINING INTO COWL.