Hard Starting when warm

[HUMTECH]

Any codes set? tough one to diagnose over the internet. As far as the glow plugs not coming on as long they are set on a timer and will come on for shorter periods of time with a warm engine. Possible leak in the fuel return system and after it sits the air bleeds out? You can always put a piece of clear hose in place of the return line at the pump and check for air bubbles while the engine is running.