1996 Collector Edition Corvette

[wxo]

you could disconnect the line at the tank and at the fuel rail and put compressed air through it

Good idea, I'll do it.

[Maverick]

I started a thread on the Corvette forum and got an interesting post this morning.

Having thought about this for a second, I also recommend that you check the fuel pressure regulator. If the regulator diaphragm has failed, and the key is turned on, when the fuel pump pressurizes the rail some fuel can bypass the failed diaphragm in the FP regulator and go back through the vacuum line which is attached to it. If this happens, raw fuel can enter the intake manifold through the vacuum line and this will go to the nearest low point cylinder intake by that vacuum port. Just a thought if the injectors check out fine.

That's a third possible cause for flooded cylinders. We now have dirt in the check valve and injectors, over pressured injectors, and ruptured diaphragm in the regulator.

Update: Now back to two. WXO just checked the vacuum line to the regulator and it was dry. Diaphragm must be good.

[wxo]

I just got off the phone with Holley fuel systems tech support. I posed the question is there an upper pressure limit on these Accel 150826 injectors. He said there was not spec like that that he knew of. Then I asked about the flooding of fuel into a cylinder. In my case, the #6 plug was noticeably black and wet with fuel when I pulled it out. Based on this, I conclude that only one cylinder was flooded by one injector. He went on to say that if the problem was related to fuel pressure, it would have affected all the cylinders. In my case the car kept running until I shut it off. He stated that the only thing that could cause this symptom is trash in the injector or a faulty injector.
He implied that excessively high fuel pressure can cause a rich running mixture to all the injectors, but not a flooding situation on one cylinder.
For what it's worth...

[wxo]

I started working on the fuel system again today. I got the new fuel filter installed and then I cut open the one that was on the car. There was a small amount of debris visible on the input side of the filter, but I could see nothing on the output side. The filter looked like it was doing it's job. I plan to remove the injectors on my next work session and then flush everything from the feed line to the injector ports. Then I'm going to back flush the injectors using this procedure: https://shop.advanceautoparts.com/r/car ... -injectors.

[MostMint]

getting another opinion - good idea. you'll find it.

[wxo]

Today, I started back-flushing the injectors to clean out the input screens. I started with #8 and didn't see anything flush out of the screen. Then, on #6, I noticed a few black specs come out. When I looked into the fuel rail port for #6 I saw this:

Just as a reminder, #6 was the cylinder that was flooded. I finished all rest of the injectors and saw a couple more that had a few specs of dirt come out of the screens.
It's obvious that Evapo-Rust was not the best choice for the job of cleaning out my fuel rail the first time. I've disassembled it and it is now soaking in Berryman's Chem-Dip. Berryman's did a fabulous job on a mucked up carburetor from a generator I recently worked on, so I'm looking forward to a spanking clean fuel rail. I believe I've found the solid evidence I need to feel confident about putting everything back together and taking a ride.
One last question is still unanswered. How did a piece of debris big enough to hold an injector open get past the input screens?

[wxo]

Yesterday's elation about the "smoking gun" was a bit premature. I found more.
Having cleaned and assembled the fuel rail and injectors,

I hooked them to the fuel lines and hit the key to pressurize them to watch for leaks.
I had neglected to hook up the vacuum line to the Holley adjustable fuel pressure regulator and witnessed gasoline pouring out of it! WOW!
This should not happen. I took it apart and found a ruptured diaphragm. I called Holley tech support and they said there were no replacement parts for this regulator. [ I can't help thinking about the failure of the Holley regulator and then I remembered something.  While tinkering with the engine some time before all this happened, I noticed one of the screws on the regulator had backed out.  There are multiple screws holding the cover on and I tightened them all.  This cover traps the edges of the diaphragm and creates the seal.  When I removed the cover and had a look, it was torn along the edge.  It's likely that these loose screws were the beginning of this whole flooding problem.  I guess in hindsight, I should have taken the time to put thread locker on the screws, but I didn't. ]   And since I had cheaped out and bought this on eBay, tough luck.
So, I installed a new OEM regulator I had and tested again. No gas pouring out, but the #6 injector was leaking a lot more than it should. I need to decide what to do about that.
In addition, one more thing happened. As I was exchanging the regulators, with the fuel rail lifted and loose above the engine, a small spacer washer dropped out and headed in the direction of the open injector ports. I can't find it and unless I do, I'm left with no alternative but to pull the intake.
These events, which might sound to the casual observer like a disaster, has at least one really positive attribute. Had I not forgotten to hook up the vacuum line to the regulator and spotted the gas pouring out, I would have ended up with a repeat of the gasoline flooding situation. That's a disaster.
And, although it's not something I relish, pulling the intake (which, I believe, is a dry intake) would have the benefit of getting a look at the conditions underneath and getting the top of the engine cleaned up to boot. So there you have it...The beat goes on...

[MostMint]

options to consider:
if the intake is aluminum and the washer is metal maybe you can get it with a small magnet?
pull the plugs out and pull a vacuum on the hole it fell into
pull the plugs and see if it will go out a plug hole on compression
its a small washer it'll probably just go through the engine - assuming it went in there in the first place

[wxo]

All good suggestions, Andy. The intake is aluminum and I've tried the magnet down the injector hole without results. All the plugs are out of it at this time. I don't have any idea of what the path looks like from the injector hole in the intake to the combustion chamber, so I'm not able to visualize where this washer might be. I inserted a hose under vacuum into the injector hose and was surprised to suck up gasoline. I guess the floor of the intake is still flooded with gas. Even though the washer is small, I don't like the idea of taking a chance on it bouncing around inside the engine. I'd rather pull the intake and be sure it's not there. Hey, this is a long term project and I want to get it right.

[Basement Paul]

You could blow air down the injector hole. With the plug out, it might come out depending on where in the stroke it is. You may need to turn the motor over so the intake valve is open.

-BP

[wxo]

These are all good suggestions, but my focus needs to be knowing whether the washer is in there or not before I start up this engine. The only way I see to do this is to remove the intake. If It's not anywhere in there, all is good. Seal it up and move on. If I find it in there, all is still good. Seal it up and move on. Looks like a win-win to me.

[Fred32v]

Can't see what happens next.

[wxo]

I'm going to slow down and step away for a while and regroup. Christmas is coming. Maybe more next year.

[wxo]

Obviously, I can't stop thinking about this thing. I did some searching today and found what I was looking for, a fuel rail fit, adjustable fuel pressure regulator to replace the faulty Holley that caused this last, sad episode. I found a great price on Amazon to boot.

BTW: I was able to return the Holley regulator to the seller on eBay even though the ad stated "no returns"

[MostMint]

you could get another injector