0046 car fire this afternoon

[sunlion]

I'm safe and the car has some minor damage but pretty scary few moments.

Lost most power in my 912e going up a slight incline from a stop, while pulling over noticed flames out the deck lid. Fire was in left carburetor, soon spread to interior. Had a can of extinguisher which was soon empty. Luckily, passerby had a real extinguisher and got the flames extinguished within a few minutes. Still smoking heavily when the fire dept arrived and they put out the smoldering. Had the car towed to my shop.

Carbs were balanced a few weeks ago, was running better, but with frequent popping from left carb and no back firing from the muffler. Only today, had scheduled an appt to have it looked at. All the fuel lines were intact - I checked once I was sure everything was out and had cooled down. I guess, with a popping carb, the intake valve is open slighlty when the spark is delivered. When I accelerated to go up the hill, it probably got a good jet of fuel which was ignited in the carburetor. Any other thoughts on why this happened?