GM part # 19178983. This may be a 2-ring kit (per injector).
ACDelco 217-3367. 2-ring kit
ACDelco 217-3113. 9-ring kit. For 4 injectors + may include fuel supply tube o-ring.
Rockauto lists kits from other brands, too. The kit that @db4690 linked to at Napa is by Fel-Pro.
Yes, GM specifies oiling the o-rings.
I ordered the Delco kit from Rock Auto shortly after making my last post.
No, I didnāt install them dry. That kinda goes against everything I wrote in my post. 
I want to thank everyone who has been trying to help in this thread! While im not out of the woods yet, you guys (possibly gals) have been a tremendous help the whole way here.
No experience w/this specific fuel injection design, but I canāt see how damaged o-rings would allow fuel to flow from the injectors, unless they were somehow pushing on the pintles. At least for the injectors Iāve dealt with the O-rings are there to prevent air from leaking into the intake manifold, not to prevent gas from leaking from the injectors.
The diagram appears a little blurry on my computer, hard to read the writing, but from what I see that 120-grey wire you mention should have battery voltage on it when the pump is powered. Does it? That is the power supply for all of the injectors, and should have battery voltage on it at all times the engine is running or cranking. When a gas-spurt is needed from an injector, the engine computer grounds the other side of that injector, causing current to flow through the magnetic solenoid that surrounds the body of the injector, which creates a miniature magnet inside the injector, and the force of that magnetic field pulls on the plunger and opens the injector so fuel sprays out the end. Itās like one of those gadgets with a spring loaded handle you put on the end of a hose to wash your car, but you canāt adjust the flow rate, it is either on or off in other words. The computer adjusts the amount of fuel delivery by varying the amount of time the solenoid is grounded instead.
So if you had one of those gadgets on the end of a hose, and it sprayed all the time the water was turned on, rather than only spraying when you pulled on the handle, youād know how to debug that, right? Probably the return spring inside has broken. Or the seal at the tip isnāt sealing. This problem seems identical to that. Itās a little more complicated of course, for one thing, gasoline is involved which is dangerous to spray around.
All the injectors are bad b/c their seals are not sealing or their plunger isnāt returning to home to seal them off when their āhandleā is released.
The āhandleā is being pulled all the time, meaning the other side of the injectors are being held at ground voltage all the time, instead of just the short interval when they are supposed to be injecting gas.
@GeorgeSanJose, this is a different type of fuel injector than you are used to. Youāre probably thinking of an injector that mounts between the fuel rail and the intake manifold (which I was at first, too). On this engine, the injectors actually mount within the fuel rail. The fuel rail is a gallery/passage cast into the lower intake, and the injector bores intersect this gallery. Holes in the gallery connect directly to the intake ports. The injectors plug into these holes, sealed with an o-ring. Fuel enters the injectors in their middle, instead of one end.
Hereās a picture that illustrates this. The fuel gallery/passage/rail is #6, the injectors #7. If you click on the picture, Itāll open larger in another window. If you click it again, it may get even bigger (same with the electrical diagram I posted above).
Oh my, I see what you mean. That makes this problem more difficult b/c the problem could be the injector, the o-ring, or the surface it seals against. Thanks for explaining.
Exactly, I took for granted you guys knew it wasnāt an injector on rail design like normal. Its a fantastic little engine, easy to maintain, rebuild and generally work on. The injectors are held down by a long, flat forked bar and the injector housing tabs. Itsā¦ a pain.
I donāt think its a crack(s) in the rail itself, or the injectors themselves. One O ring was split (they are so loose/oversized its crazy) and another one was justā¦ gone, so I assume it too split and is inside the fuel rail and hopefully not the cylinder. Iāll blow it all out with compressed air to be sure.
I think the lower rings were too large and probably didnāt make good/any contact with the ports. Ill test that theory today with a cheap felpro gasket kit (5 bucks). Iāll just install the injectors, plug the fuel fuse in, and try cranking it. I should know in about 30 seconds if anything has changed!
FWIW . . . Felpro generally makes pretty good gaskets
My first choice would be OEM . . . my second choice would be Felpro
I like Felpro, Iām just saying the price is cheap
I reinstalled the injectors, and no more over fueling! The upper O ring on injector 4 leaked for seemingly no reason, so I used an O ring from an older injector. The injectors went in so much better this time, like night and day. I really think the lower O rings shipped with the new injectors are too large.
So far, so goodā¦ next is the P300 sorting.
You guys were awesome with this problem, maybe you can help me with my main one?
Youāre still getting the p0300 ā random/multiple misfires across all the cylinders? First make sure it doesnāt go away after driving the car a few days, the computer might just have to do a re-learn now the injectors are working again.
Misfires across all cylinders usually means thereās something common to all the cylinders that is the problem. So youāre looking at a problematic ignition system, ignition timing, or faulty air/fuel mixture. Less likely, but still possible is an exhaust system problem, compression, valve timing problem, or inaccurate sensors.
Or maybe it isnāt misfiring, and itās just a bogus code. Do you believe it is actually misfiring? If so, where Iād start is to bring all the routine engine maintenance up to date, then probably a throttle body inspection and throttle body cleaning, paying attān to the state of the MAF. If it looks to be covered w/gunk, give it a good cleaning. A gunked up MAF is a fairly common reason for misfires across all the cylinders.
If you could figure out a way to get access to real time scanner data, that would be very helpful for this problem. Especially fuel trim data. Is that possible for your car?
BTW: Problems w/the throttle position sensor can cause this too, so correct those first before starting down this road, if you havenāt already.
