Got my new O rings installed and no longer having leaks at any of the fuel injector rails (91 L98). BUT - cranked her up and am leaking fuel at the schraeder valve and at the O ring where the fuel outlet tube connects to the fuel pressure regulator.
I had the cap off of the schraeder valve and was able to stop that leak by putting the cap back on. But - the valve itself was loose. When I tightened it down it did not help. Is the proper replacement simply a new valve out of a tire stem? Guess I will head to NAPA after I cut the grass in the morning.
I have a bunch of spare O rings. I will take the fuel rail apart again and see if I have the correct-sized O ring for that particular orifice and try, try again.

make sure whatever part you use it's fuel proof.

nitrile is the best bet for o-rings and seals.

You should be able to replace the valve... it's not just a tire valve, it's fuel proof.

Ron - you can pull the schrader valve out with a schrader valve removal tool that costs about $5. Otherwise I have had success removing them using thin needle nose pliers.

Like Andy said, they are the same style as a tube/tire valve, but make sure it's fuel safe.

For the o-ring, when you check it/reassemble it, just make sure it's not pinched or cockeyed when you put it in, that could be your problem if the right size was already used.

Found that I used an O ring that was too thin. Replaced it with a thicker one that gave a much better seal. The humidity and heat here in Michigan has been brutal this week. I don't have AC in my pole barn but even with 3 fans blowing air around I am still drenched with sweat when working on the car. This is NOT fun.
Anyway - got her back together and trying to start it. Crank and crank and get it to run a bit while the starter is still cranking. As soon as I release the key it dies. Had one helper watching for fuel leaks and adjusting the distributor and another with a timing light. Got the timing right on but no start and the battery is dying. Also noticed a very small amount of fuel at the intake manifold side of the #8 injector.
So - she is on the charger over night. There is quite a bit of space in the fuel rail opening at the top of the fuel injector. I think I will pry #8 downward 1/8" or so to see if it will seal a bit better at the manifold side. I will also be checking the routing of my new spark plug wires again to insure we did not get them fouled up.
Then off to Florida for a few days.
Somehow I broke the plastic off the coolant temp sensor while messing around with things.
Grrrrrr!

Still leaking at the #6 injector. We could see that the 6 and 8 injectors were sitting a bit high into the rails so pulled them down farther into the manifold. Now they leaked at the rails. Noticed that there is quite a deep bore in the fuel rails so got the bright idea to pull those two injectors and install an extra O ring in the rail before re installing the injectors.
Now #8 is leak free and #6 leaks.#!&*%!
Here are some extenders that FIC offers. They are not open and due to the holiday will not be available until Tuesday so I am unable to ask them for advice.
http://fuelinjectorconnection.com/shop/viewitem.php?productid=180
My worry is that these are 1/2" extenders. If I put these on one injector then the entire fuel rail might be up too high and cause them all to leak.
My problem is that there is obviously too much room between the fuel rail and the intake manifold and the Bosch IIIs are too short to fill the gap. The FIC website says these are modified so that they match the length of the stock L98 injectors but I don't think they do.
Any ideas? I found myself hoping the dang thing would catch fire and let me collect on the insurance. Sad that it has come to this.
Good news is that I no longer have to drive the U-Haul to Florida tomorrow so at least I can stay here and work on this.

Ron, I put those into mine and had an issue, they sent a new set out with the double O-rings, that fixed the problem. Of course mine was an LT1, don't know if they are different than the L98s.

Thanks - I will see what they can do for me when I call Tuesday.

I had a great response over at CF. You may want to save this for your records if you are ever involved with the TPI system:
http://forums.corvetteforum.com/c4-te ... 1-l98-fuel-rail-leak.html

I have tried almost everything I can think of. Inspection of the fuel rail "well" where the injector sits. Used a jeweler's loupe and could not see any scratches or burrs or dirt. We inspected the new O rings under magnification and they are defect free. Tried with lots of Vaseline and again with dish soap. After 2 tries today I still have 2 injectors at the back of the driver's side fuel rail that leak and are now worse than ever.
I plan to use a micrometer to measure the bores and compare them to the non-leakers. I will then swap the front 2 injectors on that rail with the leakers and see if that makes a difference.
If no luck then I plan to call Jon at FIC on Tuesday to see if he has any advice or will maybe swap these 2 out for 2 new ones. If I find that the rail's bores are worn (highly unlikely) then I will buy a used fuel rail from Vette2Vette.
Interesting that I can only really see the leaks after cranking the engine over for a few seconds. I do not have the plenum or the throttle body on and the runners are loose. Dang thing started to run during the last cranking session! I had to shut the key off! If it had kept on running I bet the RPMs would have soared!!!!
I need to get this solved so I can fix a couple of other small problems and get the car on the market.

Are you as sick of this post as I am?
Sending two of the injectors back to Jon at FIC. Each port I move them to leaks.
Not sure he will warranty them so I told him I would pay for two more if they are no longer covered.
This SHOULD solve the leak so I can get on to fixing the other minor problems with her.
Probably missed the selling season and have incurred another value drop.

Geeze! I hope the replacement replacements do the trick!!!

E-mail from Jon Banner of FIC this morning: "Two coming your way".
What a great company!!!!!

Jon rocks!

I sure hope that fixes it... I have never had an issue with injectors leaking like this.

Could they have been cracked a little?

Injectors came in today but I am going to wait till tomorrow when my son can come over to assist. I have found that an extra set of hands are nice to have when installing the fuel rail.
Thanks Jon !!!!

The new injectors worked! Wish I had realized this earlier.

Awesome!