Quickie on fuel pressure reg & hard warm start

[TPyles]

I have read a lot on the 5.3 hard start when warm. I had mine in a couple of months ago and it wouldnt hard start while at the shop, mostly because it was cold. There are no computer codes or trouble lights. I pulled the small vacume hose off the fuel pressure regulator the other day and some gas dribbled out...Does this mean the fuel pressure regulator is bad?? The truck is a 1999 Silverado 4x4 with about 180,000 miles. Other than the hard warm start it runs like a top!! I appreciate any insight Thanks for the help.

[brandon093]

I am having the exact same problem with my 99 5.3 Silverado and I can't figure it out. I did replace the Fuel Pressure Regulator and I have had no luck yet. Someone told me that it might be a bad relay switch that is telling the PCM that my oil pressure is too low to start. Still troubleshooting that idea. If I figure it out I will let you know.

[GMMerlin]

A fuel pressure regulator that is leaking at the vacum port is considered faulty and can cause hard starting.
Also a dirty throttle body can cause a hard start warm

[jdstone]

Originally Posted by TPyles

I have read a lot on the 5.3 hard start when warm. I had mine in a couple of months ago and it wouldnt hard start while at the shop, mostly because it was cold. There are no computer codes or trouble lights. I pulled the small vacume hose off the fuel pressure regulator the other day and some gas dribbled out...Does this mean the fuel pressure regulator is bad?? The truck is a 1999 Silverado 4x4 with about 180,000 miles. Other than the hard warm start it runs like a top!! I appreciate any insight Thanks for the help.

MIne had to crank 3-5 seconds to start (hot or cold) and had rough idle during the last few weeks. Fuel pressure was normal at about 50 psi. I had gas in the vacuum line also. There should be no gas there! It means that it is sucking gas thru the regulator and into the intake causing an excess rich mixture. Changed the easy to replace $50 regulator and now it starts instantly and has perfect smooth idle! Thanks to the messages on the forum that helped diagnose the problem quickly!

[mastanga]

My 1999 4.8 starts fine in the morning but once I have run it for a while then let it sit (even for hours) it is hard to start and idles rough until I take off. Sounds to me from all the notes that it is the fuel pressure regulator. Is the regulator next to the intake under the Vortex shroud? Thanks

[mastanga]

I changed the fuel pressure regulator ($70 for the little thing) and it fixed the problem. I noticed when I pulled off the vacuum line that there was a lot of gas in the line. I want to thank everyone for the help this forum is great.

[rocky3d]

This is a very old thread but I am having a similar issue with a 2004 Suburban. Starts great when the weather is cold but when its warm weather its hard to start, usually takes 2 to 3 tries.

I have cleaned out the throttle body and replaced the fuel pressure regulator, fuel pressure seems right at about 50 psi. Wondering if anyone might have another suggestion? I was hoping the new fuel pressure regulator would fix it like most of the posts say it did.

Thanks,
John

[j cAT]

the pressure spec is 53-62psi. on a ignition on cycle and engine off , the pressure should rise to 60 psi. if lower its saying the fuel pump is weak.

when the engine is running the pressure must be at or above 53psi. if not at least 53psi . you have pump problems.

when it gets to 50 psi this is the threashold of no start. depends on pressure guage being accurate. one drop/shock it will need be calibrated.