Exactly what is the link between mixture control and the engine fire that seems to be caused by overpriming? Other than that both can be classified as some sort of engine mismanagement?
Perhaps I should have outlined the details more clearly.
They apparently taxi with the mixture full rich causing the plugs to foul (mixture error one). During the runup there was the resulting out of limit mag drop. The pilot and CFI, also apparently, didn't know how to clear the plugs by leaning the mixture at a higher RPM (mixture error two). It was a 2100' MSL airport, but leaning during taxi should also be done at sea level.
One could argue that if they had adjusted the mixture properly during the taxi out, they wouldn't have had to do a hot start, which resulted in an unresolved induction fire.
So the pilot did not try to stop the fire by simply keep on cranking to pull the carb-fire back into the engine (with the throttle fully open and the fuel cut off)? That is the procedure for all carburetted PA-28s I know.
No.
Control of mixture during hot start (mixture error three). No induction fire resolution attempt (mixture error four).