Gas coming from the vacuum connection on the fuel pressure regulator

[MojoMan317717]

1996 Lumina 3.1 with 145K

Has had a hard start issue for as long as I have owned it. Never bothered to care, as it always starts when I give it a little gas, or on the second or third try, but for whatever reason I have decided to care and so I've spent several hours reading on this forum.

From the title it's obvious I have fuel coming out of the vacuum connection on my fuel pressure regulator. I read in another thread that I should pull the vacuum line and then cycle the ignition on and off a couple times to see if fuel escaped from the vacuum connection on the fuel pressure regulator. It did.

Does this definitively prove the fuel pressure regulator is defective?

[Airjer_]

There should be no gas coming out of the fuel pressure regulators vacuum port. If there is than the regulator is bad.

[MojoMan317717]

It goes without saying that I'm going to replace the FPR, but does it play a role in the starting? I suspect the obvious answer is yes, but I want to hear it from someone who knows.

I realize there may be other contributing factors like the IAC for example.

[maxwedge]

Yeah it can cause a momentary flooding condition.

[Airjer_]

And it can also cause vapor lock. The fuel needs to be under pressure in order to prevent itself from boiling in the fuel rail after a hot engine is shut off. The leaking regulator will allow fuel pressure to drop in the entire fuel delivery system, more importantly in the fuel rail. The fuel will now boil into vapor. Injectors work by injecting liquid fuel not vapor. So now you have to crank the engine over long enough for the fuel pump to push the fuel vapor out of the fuel rail and replace it with liquid fuel.

You know have a classic symptom of extended crank The most common source of the problem in GM vehicles is the fuel pressure regulator with the fuel pump itself in a close second.

[MojoMan317717]

Great info guys! I knew this forum would have the answers I need! I promise to report back after I change the FPR this weekend.

[MojoMan317717]

OK, I guess I should not have promised to report back, because I obviously forgot. So, to wrap up this post, I replaced the fuel pressure regulator and sure enough the hard start issue vanished. It now starts immediately. Also, just FYI, it was really easy to replace.