Just purchased a 2000 5.3 LS Silverado. After motor is shut down for a few hours, it starts hard. It seems like fuel isn't getting to cylinders fast enough. Injector problems maybe? It doesn't even like to fire until immediately after i turn the key back. Is this common with newer 8cyl Chevys? Runs beautiful after it starts though.

A leaking fuel pressure regulator, or injector can flood the engine making it hard to start when the engine has been turned off a few hours. You can pull the vacuum hose off the regulator to see if there is fuel in the vacuum hose.

//2000CAYukon

I have seen several of these with bad fuel pump check valves. Put a fuel pressure guage on it after it sits for awhile. Watch the guage while cranking, if the fuel pressure doesn't come up until it just before it starts (most will run on ~15 PSI, but not well) the pump is bad. If it comes up right away and still doesn't start, then it is probably flooded, but I doubt all 8 fuel injectors would go bad at the same time. If it was just flooding one or two cylinders it would probably just miss until the fuel burnt off.

On a 5.3 as said check the fuel pressure regulator real close.
And Check that fuel pressure.
You need 55/62 lbs of pressure.
Specs on it is 55/62 lbs of pressure
Here is some guide lines of fuel pressure checking.

Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 55-66 fuel pressure.
Cold start should be 55/62 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 55/62 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
If pressure does not come up with return line pinched or blocked off.
Go to fuel filter and hook a gauge direct to a line at fuel filter.
Pressure should come up to 75 or more and will hold after fuel pump is turned off.
If it leaks down there after fuel pump is turned off it is LEAKING BACK THREW PUMP CHECK VALVE OR PUMP MODULE LINES.
Post back your fuel pressure readings.
MT

Just purchased a 2000 5.3 LS Silverado. After motor is shut down for a few hours, it starts hard. It seems like fuel isn't getting to cylinders fast enough. Injector problems maybe? It doesn't even like to fire until immediately after i turn the key back. Is this common with newer 8cyl Chevys? Runs beautiful after it starts though.

other than fuel problems, if this is simply hard start cold, I would check resistance of ECT , if this is incorrect, the computer may not adjust for cold start.....you do not have to remove, just measure the resistance of the sensor terminals compare with sensor on driver side of engine next to #1 cylinder should read the same......this one goes to dash temp gauge......

Thanks guys, sorry for getting back late. It pulled the vacuum hose and there was some fuel residue. I cleaned out some of the parts and the starting hasn't been a problem yet. I think I will replace the pressure regulator (70-90$?). Thanks for the help.