The combination of the pre-heater and the work the mechanic did lately made the plane start easy and warm up quickly.
After the fire the mechanic looked over the engine. A few items needed taken care of such as the priming system.
The Archer has a 2 cylinder priming system.
Two of the cylinders have an insert that has two opposing holes to spray fuel into to the two cylinders for priming purpose. Of the four holes in the two inserts three were blocked with carbon buildup the last was not spraying the fuel it was putting it in, in a stream. Not conducive to good combustion. This contributed to the fire by making the fuel run out.
To start: the engine was primed with 3 pumps and the engine started after it turned over a half dozen times. It also reached operation temperature in about 10 minutes.