Hard Starting When Warm

[bowdownbowser]

Hey everyone, so my 07 Sierra NNBS 5.3L Flex is having trouble starting when the engine is warm. If i start it in the morning when its cold it starts fine but if I start it then turn it off and let it sit for longer than like 30 minutes it cranks for about 4-5 seconds before starting or it will start and stumble then go back to normal idle right away. Last week I replaced the injectors and today I replaced the pump with a new replacement AC Delco pump and I am still having the issue. There is no Fuel pressure regulator on this and the filter is built into the pump so as far as the fuel system I dont know what else it could be. Is there something I'm missing here? Any help is greatly appreciated.

 

[danocywg]

Did you ever get a fix for this, cause I'm having the same problem!

[Mike GMC]

Did you check the fuel pressure?  Unfortunately, new parts don't necessarily mean properly functioning parts.  You may also want to look at the IAC, TPS and clean the throttle body. 

[davester]

maybe also check for leaks in the air intake?