I have a 99 Silverado Z71 4WD, 5.3 liter. After driving the truck a short distance and then shutting it off it has a hard time starting when it sits for awhile. Fuel pump was replaced in Jan, and fuel pressure regulator was replaced last week. Still have to crank it several times to get it to start. Any ideas on where to go next?

I would get a pressure gauge on it.
I had two 6-8 months old fuel pumps fail the same way.
Bob B

I have not had a chance to put the pressure gage on as of yet, but I found that if you turn the key to on and let the fuel pump prime itself the truck will start with no problem. Does this sound like the fuel pump or any ideas of what it could be?

If I remember correctly, there is a check valve in the fuel line that keeps the pressure from dropping. I would suspect a leak. I don't know where it is though, so hopefully somebody else can tell you.

You need to replace the Fuel Pressure Regulator.. I had the same syptoms in my truck.

I checked the pressure from the fuel pump, turns out that it is 4lbs under the minimum even when running. When the truck is shut off and you let it sit the pressure falls off and will not allow the truck to start until it builds up pressure. Replacing the pump today so hopefully that will solve the problem.

I have replaced the fuel pump now and the fuel pressure regulator and stil the same problem! Any ideas where I should go next?

You need to run a full fuel pressure test.

If You fuel pressure is to low.
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