Foosking

I had a fuel injector leaking small amounts of fuel for a month now. A buddy of mine who is mechanic (redneck) said the o-ring was bad. Alot of work for a simple o-ring so I put it on the back burner.
Then 1 day I am driving on I-55 in Memphis and noticed my Check Gauges indicator was lit then noticed my temperature gauge is above 260 and pegged at max "around 300 I would guess" so I pull over to take a look.
I see no steam or overheating signs under the hood. I see no fluid in the radiator so I put in a gallon I had in the back and notice it running out on the ground. I track down the leak and its the passenger side freeze plug. Called my buddy and put it on his trailer and towed it home.
He said he would be able to replace the freeze plug without dropping the engine or taking it out. I then decided to fix that fuel injector too and other things like the a/c compressor which is leaking and my radiator which last year when I flushed it look really bad so I ordered the radiator on ebay for $67 free shipping which was a perfect fit but first the freeze plug, check for leaks then work on the other stuff. He broke the plastic connector on the crankshaft sensor so I ordered one of those too.
With the freeze plug replaced and a new crankshaft sensor I filled with water to check for leaks then started it up, turned the heater on and filled with more water. No leaks so that repair was successful. No water in the oil and no water coming out the exhaust so we were confident that the head gasket was still good.
Now comes the injector and we pull the radiator, Throttle Body, Upper Plenum, Fuel Rail and injectors, hoses, Thermostat and housing, and temp sensor. The center 4 injectors were very badly rusted and the leaking injector was not the o-ring but leaking from the side of the rusted injector. Where the injectors sit in the lower intake manifold were full of water. The outer 2 caddy corner injectors has no rust and looked really good.
I ordered 6 new injectors, temp sensor, 160 degree thermostat, radiator, hoses. plugs, and TB gasket. After about 2 weeks we got it all back together as it rained nearly every day or so. It started up and ran smooth and I thanked my lucky stars as things like these always have some unforeseen issue for me.
I changed the oil and filter and confirmed no water/fuel in the oil.
A few days later I went to visit my parents about 2hrs away and after filling up with gas I headed out and it died on me. My buddy came with his trailer and it started up and drove it on the trailer and it started up and drove off after towing it home.
When we started working on it it would not start. We tried all we could think of then he decided to put in the old crankshaft sensor and it started right up.
I went and got another new one and we got 2 more from the junk yard and none would work but the old one. During this troubleshooting the engine locked up. Turns out cylinder #2 was full of fuel. I changed the oil again and it smelled of gas and was black. After that it started up I made a 300 mile trip for business. I drove it to visit my parents 150 miles away and now its locked up again. I pulled the plug and it is wet with fuel. Turned it over and compressed the fuel out of it, put the plug back in and it started right up.
So now my question is what could be causing it to fill with fuel when the car is off?
The fuel pressure regulator seems good as I pulled of the vacuum line and its dry with no fuel smell.
It does have a little blueish smoke when started but quickly disappears.
If the injector is stuck open how does it run normal when started?

Injuneer

The injector is leaking. Put a fuel pressure gauge on it, let the pump prime (without starting the engine), and watch how high the pressure builds on prime, and then how fast the pressure bleeds down when the pump shuts off.

Pull #2 plug, and if its fuel soaked and carboned up, the injector is leaking while it runs.

Foosking

Done that. It was around 43lbs and when turned off slowly decreased. It took about 30 seconds to reach 0.
Is it possible to leak while it runs without noticing?
I think I am going to replace it with one of the originals I took out.
If you cant rely on new parts what can you rely on?

Injuneer

Pressure dropping from 43psi to 0 in 30 seconds is not "slowly"..... there's evidence that something in the system is leaking badly. The GM spec on pressure loss is something like 5psi in 10 minutes.

A leaking injector will drop the pressure that fast. Takes very little fluid loss to reduce the pressure to 0, because liquids are non-compressible.

Fuel leaking from the fuel pressure regulator vacuum compensation line will also cause rapid pressure loss, but you indicate you have checked for that already.

GaryDoug

If you find nothing wrong with the injector, it's possible the wire going to injector #2 is shorting to the engine somewhere, which would turn it on. That might explain why it is intermittent.

Injuneer

With the LT1 fuel rail, its very easy to raise the fuel rails, and pressure the fuel system to look for a leaking injector. Don't know if it's as easy on the V6, but that's one way to look for the problem.

Foosking

Sorry I meant when I turn it off it takes 30 seconds to reach 0.
V6 fuel rails are a PITA as its mostly under the cowl.

Injuneer

OK.... when you turn it off (or if you turn the key to prime, and the pump shuts off because you didn't start the engine) the pressure should hold close to 40psi. It should not drop under any circumstances to 0 in 30 seconds.

Foosking

I replaced injector #2 with the old one and all is good now. My buddy blew into the top of it an fuel blew out the other end. He is still giving me a hard time about this. He originally told me he would only replace the one that is leaking with a junk yard part. I told him its only a matter of time before the other 3 badly rusted out ones fail and he said if it aint broke don't fix it. I explained my logic of doing it all at once and avoiding having to tear into again in the future which would cost more in time and gaskets. We couldn't agree and I could not understand his redneck logic.
He also gave me crap about replacing both of my headlights when 1 of them went out. Apparently he likes 1 new and 1 yellowish looking lights.
Anyways fuel pressure with key off never decreased from 43.
I changed the oil/filter again (3rd time) which was very thin and black from the fuel. Gonna run this for a week or so to make sure all is good then put in my good stuff.
Also going to drain the radiator and put in antifreeze and distilled water. I have been running straight water and flush.