[Arrowhead1952]

Liquid fuel vapors will only combust within a certain range of concentrations; too “lean”, they won’t burn, too “rich”, they won’t burn.

Remember “flooded carburetors”? Too rich a mixture. .....

I was a GM mechanic from the late 60s until I joined the national guard exactly 41 years ago today. We used to take a pan of gasoline and throw lit matches into it and they would go out. Then we put a fan on one side of the pan and the vapors would explode.

[DuncanWaring]

Sounds fun!