Please help.....Ok so my 2000 Tahoe with a 5.3 in it starts and drives perfectly. It isn't giving me any codes either. But if I turn it off after it is warmed up it won't start until it cools down (about 45 minutes later) . does anyone have any idea what it could be?. Also I recently replaced the fuel pump and fuel filter. Also all o2 sensors, I ran fuel cleaner through it, and I replaced the coolant temperature sensor.

 

When you say start do you mean it's not cranking over or not firing up ? That info description is very important.
If not firing up try flooring the gas pedal and see if that makes a difference on how it fires up.

 

+1. could be fuel pressure leak down either thru the injectors or fpr. clear flood mode start will help determine if that is the direction to follow.