Hard Starting when warm

[HUMTECH]

Let me get this straight, hot or cold if you shut it down it will refire if you try it right away? If you let it sit for 15 minutes it has an extended crank? Is there lots of smoke when it fires after the extended crank? If so you may have leaking injectors causing a flooded condition, which if left overnight the fuel will seep past the rings and into the crankcase. Can also check for fuel contamination in the oil which can confirm leaking injectors.