Fuel Rail issue - erratic idling/stalling

[csheridan]

I recently did a bunch of work to my Cobalt, which involved removing the fuel rail. I fixed all of my problems, but my idle went downhill. I heard a hissing noise coming from around the intake (so I thought), so I removed the throttle body and intake manifold to check out the o-rings (which were new). Everything looked ok, so I cleaned surfaces and reinstalled.

I started the car up and immediately heard the same noise again. This time I realized it was coming from the fuel rail. I placed both hands on either end of the rail and pressed down with decent force. The hissing stopped, and idle returned to normal; however, the problem persists since I don't know how hard I should be pushing these injectors back in....

So, how much force is needed to properly seal the injectors?

Thanks!

 

[YelloEye]

What year and motor is your Cobalt?

If it's one of the multiport fuel injected motors the fuel rail is only held down with a couple of bolts held in at 89 lb in (keep in mind that's inch pounds, not foot pounds)

It sounds like you might have a bad injector o-ring somewhere there.
http://www.autozone.com/repairguide...upply-Manifold-Injectors/_/P-0996b43f80cb16e2

 

[csheridan]

It's a 2008/2.2L.

It has to be an o-ring because when I move it around, it stops when it reaches a certain position. I actually left one bolt out because fully tightening them actually made it worse.

I called autozone. The o-ring (upper and lower) kit is under $10.
I'll change them out and get back to you.

 

[YelloEye]

Ah yeah, that sounds like an o-ring.

 

[csheridan]

Ok. I got the new o-rings, but it's still hissing. What are the little plastic cups that slide over the end of the injector (bottom end)? I remember when I first pulled the fuel rail out, it took some effort. Now it seems to just kinda sit in the cup, which has to be the reason I'm hearing the leak. If you look at my previous threads, once this is fixed, my car will be running perfectly (I did a major job to it a little while back that you helped me through, which was an overheating issue).

 

[csheridan]

Ok, I realized these are the injector insulators. I'm nervous about this because it's night time and I can't get any parts right now. I hope it's safe to drive because I have 20 miles to work in the morning. I just don't understand why it's leaking. I can't see any fuel residue around the injector itself, I just hear air because it's not sealing in the cup.

 

[YelloEye]

Odd. I'm not real sure why that would still be leaking after replacing the rings.

 

[csheridan]

Alright. My parts came in. I ordered injectors AND the insulators. I know exactly what happened now. I don't believe it was the injectors, but whatever, it has new ones now. Lol.

When I would try to put the old insulators back in, they would just kinda sit in the injector cups. They were too swollen (ethanol in fuel perhaps?). I lubricated the new ones, placed them in the cups, and they slid down until they seated in the cups just fine. Put the new injectors in, fired it up, and now she purrs like a kitten.

After ALL of the work I did to my Cobalt, I finally think it's good to go now. I drove 20 miles to work this morning and no MIL, no erratic idle, RPMs held steady at stoplights. Such a relief!

So, in conclusion, I think the diagnosis was swollen insulators that were allowing air to pour out.

 

[YelloEye]

That hadn't occurred to me, but could certainly do it! Congrats on getting her figured out!

 

[csheridan]

Thank you!
And thanks for your suggestions.