ENGINE BACKFIRED AND EXPLODED UPON IGNITION AFTER SITTING FOR A WEEK. ENGINE WAS COLD AND IN COLD WEATHER. 3 FOOT FLAMES, MINOR BURNS AND INJURIES SUSTAINED ER VISIT FOR SMOKE INHALATION WHILE EXTINGUISHING FIRE. VEHICLE WAS PARKED ON PRIVATE PROPERTY. A NEIGHBOR'S CAR THE SAME MAKE AND MODEL SIMILAR YEAR DID THE SAME THING A FEW WEEKS AGO.