Fuel Pressure Problem?

[MILLERTIME651]

I have a 99 Silverado 4x4. My truck starts up rough every once and awhile. It will start fine when i first start it but sometimes after i shut it off and it stays warm, it will take a bit of cranking to get her started up again. I had the fuel filter replaced not even two months ago but the problem has since persisted.

I know someone will ask about the fuel pressure being tested but i need to have that done but i was just wondering if anyone had this same problem or an answer for this.

Help please? Thanks a lot.

[MT-2500]

Welcome to AF.

What engine?
Om fuel rai fuel pressure reg?
If so pull vacuum line and look for gas in vacuum line.

And check that fuel pressure for sure.
Fast leak down shows fuel pressure leaks.

Low pressure will cause hard starts to.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold and fuel pressure testing guide line.
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.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 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 60-66 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 in system.
Post back fuel pressure readings.

[MILLERTIME651]

I have a 5.3 V8 and i probly won't get those pressures for another week but any insight is greatly appreciated

[MT-2500]

Originally Posted by MILLERTIME651

I have a 5.3 V8 and i probably won't get those pressures for another week but any insight is greatly appreciated

Fuel pressure Specs on the 5.3 V8 is 55/62
Fuel pressure regulators is on the fuel rail and may be leaking fuel into the vacuum hose.
Pull, hose after a hot or cold soak and see if vacuum hose has gas in it.
If so replace fuel pressure regulator