S10 hard starting problems

Hello, i have a 2001 S10 4.3 2wd. It is hard to start only when warm takes about 5 to 10 seconds of cranking before it starts. On a chilly morning starts right up. If you stop at store and come out within 5 minutes starts right up. if you let it sit 10 to 60 minutes where the engine is warm or now even if the temp is above 60 degrees its hard to start. It sits overnight and it cranks fine it is only throughout the day this happens. Truck only has 65k on it and this is driving me crazy.Runs great when its running.No engine light and already changed the fuel filter. any idea's???

See if fuel pumps runs with key on engine off- next time you think that it will hard start.. you may be waiting on the oil pressure to build up and trigger the fuel pump through the oil pressure switch if the fuel pump does not activate for 2 sec with key on, engine off.

Or put a fuel pressure gauge on it and see if pressure drops-when you shut the engine off.... you may have a leaky regulator and are filling the intake with fuel and it takes longer to start because it has to clear the flooded condition. Short stops- there isn't enough time elasped to flood the intakes--over night starts- the intake has drained into cylinders, or evaporated the excess fuel....

i have done that and the fuel pump does whine when you turn the key on and the weird part is when it sits overnight it cranks right up in the morning