Does anyone know what the fuel pressure is suppose to be on a 99 5.3? My work truck is getting hard to start and getting kinda of sluggish. So I think its the fuel pump. It has a 174000 miles on it. It has been changed once I was told. If it is the fuel pump does anyone know if anyone makes a out of tank fuel pump. I know holley has one but I don't know if it makes enough pressure. It would be easier if I put one in the frame rail, if I ever had to change it again.

Put a fuel pressure tester on it , start the truck and it should read 45-55psi. Have you changed the fuel filter?

My brother-in-law's truck was the same way. It would crank for a while before starting the first time. After that it wasn't as bad. It was the fuel pump.

I know that they make aftermarket in-line pumps, but getting in the tank isn't all that hard. Just have to have a few buddies to help lift the bed. This is the easiest way we have found to do these. We've done 2 so far on different trucks.

If you do put a new one in the tank, go GM. Aftermarkets are not the greatest and you will probably be doing it all over again in a few years.

My brother-in-law's truck was the same way. It would crank for a while before starting the first time. After that it wasn't as bad. It was the fuel pump.

I know that they make aftermarket in-line pumps, but getting in the tank isn't all that hard. Just have to have a few buddies to help lift the bed. This is the easiest way we have found to do these. We've done 2 so far on different trucks.

If you do put a new one in the tank, go GM. Aftermarkets are not the greatest and you will probably be doing it all over again in a few years.
X2, always use OEM electrical parts for better life. Use to use the bed lift technic at the dealership. Lift it in the air, pull all the bolts except the rear two which were loosened. Put a dead man under the front of the bed and slowly lower the truck. The bed will rise up like a dump bed and by the time it lowers down far enough to work on it will be waist high. Alot easier to unplug the harness and fuel connections too.

I changed the fuel filter this weekend and it made a little difference, but it is still acting like it is not getting enough fuel.

Any codes? Possible leaking fuel regulator?

Any codes? Possible leaking fuel regulator?
X2, this is a common problem on these motors. Easy to install but the part is a little pricey.

The engine light isn't on and i don't have a fuel leak.

When the fuel regulator leaks, I believe it leaks internally, so you won't know you have a fuel leak.

Pull the vacuum line off and check for gas or gas fumes. Any at all and the regulator is bad.:D

I am going through the same crap with my 02 Sierra 4.8L. I have already changed:
-FPR
-Fuel Pump
-Fuel Pump Relay

First thing is buy a Haynes Repair Manual
-Listen for the pump to whine for 2 sec when
the ignition is turned to "Run". No whine=Bad pump.
-Check the Fuel pump relay and fuse (engine
compartment fuse box).
-Check for ANY blown fuses.
-Get a Fuel gauge capable of measuring high fuel
pressure
-Relieve fuel pressure first by removing the FP relay
and attempt to start the engine several times.
Key on, engine off=55-62psi ( cycle the ignition a few
times to get the highest reading)
-Start engine. The pressure should drop 3-10psi.
-Shutdown engine and moniter pressure drop. Should
not drop more than 5psi within 5 min. If it does then
there is a injector leaking, fuel line leak, or fuel pump
check valve.
-Check ur Vacuum at the intake manifold(port on passenger side). Engine running=17-22inHg
And at the FPR=12-14 in-Hg

No, I am not a mechanic, but I have just done ALL of this. Most of this is straight out of Haynes. Hope this helps you more than it did me. Enough to get ya started anyway:D .
Anyone know why my fuel pressure drops as soon as the pump shuts off. When I say drops, I mean as soon as the relay clicks it goes from 60psi to 0. I can only start it while the pump is running. Any guesses?

Thanks for the info everyone. Very helpful. I found out the fuel pump is bad isn't putting out enough pressure. So I guess in the next week or so I get to put a fuel pump in. Lucky me.

Another common problem. If you also suffer from a fluctuating gas gauge, that will be remedied with the pump change out.