Originally Posted by JimFreeh

A bad check valve in the fuel system could cause the fuel system to lose pressure after shutdown. This lets the fuel in the engine compartment vaporize, leading to a no start condition. Check your fuel pressure running and after stopping.

Another point... Spraying fast start into the intake to check for fuel/spark can lead to a false result. It's possible for the engine to "run" on fast start alone, without the aid of working spark plugs, on compression ignition alone, leading to the false assumption that the ignition system is working.

Jim