Another LT1 Stalling
Thread Starter
Le Mans Master
Joined: Dec 2003
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From: Van Steel Corvettes
St. Jude Donor '12-'13
Score, found out my mechanic just so happens to have a GM unit he uses as a test module that he'll loan to me. Crossing my fingers she fires right up tonight!
Thread Starter
Le Mans Master
Joined: Dec 2003
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From: Van Steel Corvettes
St. Jude Donor '12-'13
No go with the new GM ICM. Get to dig into the wiring this weekend, then on to the opti. Any chance the wiring to the oil pressure sending unit would have wires along with it that would cause the car not to fire? My sending unit has been replaced twice but is still wacky. I've been told it's very difficult to get to that wiring harness though.
Race Director
Joined: Apr 2000
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From: Texas
Do you have a scan tool or data logging software? I'm wondering if the PCM has a bad solder joint or two in it. Heat and vibration can cause the intermittent symptoms. On a scan tool, you'd typically see some or all of the PCM data drop out.
I would verify all the grounds are tight and I would verify the battery cables are tight. Also be sure to check the battery ground that runs from the negative terminal to the frame and check the battery leads at the starter. I had a car that would do this same thing...intermittently die. Turned out the battery cable at the starter was loose.
Next I would look in the FSM at the wiring associated with the ICM, coil, and the Opti. At least that way you only have a handful of wires to test.
I would verify all the grounds are tight and I would verify the battery cables are tight. Also be sure to check the battery ground that runs from the negative terminal to the frame and check the battery leads at the starter. I had a car that would do this same thing...intermittently die. Turned out the battery cable at the starter was loose.
Next I would look in the FSM at the wiring associated with the ICM, coil, and the Opti. At least that way you only have a handful of wires to test.
Thread Starter
Le Mans Master
Joined: Dec 2003
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From: Van Steel Corvettes
St. Jude Donor '12-'13
I've got plenty of fuel pressure, but no spark. I've had zero time to work on it for a couple of weeks, not sure when I'll get back to it. All battery connections are good. Have triple checked. Starter fires fine, so I haven't checked that connection.
Intermediate
Joined: Apr 2011
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From: KC
Well I'm not a mechanic but I would expect normal fuel pressure when she fires right up. My 96 had similar symptoms and normal fuel pressure at the shop when running, but I never checked it at home when she was dead. She finally quit running and sat for two weeks, engine would crank fine but never fire up. I read on CF to listen for the fuel pump engage but i didn't hear it. Changed the factory original FP and have put in 3500 miles with no issues.
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Thread Starter
Le Mans Master
Joined: Dec 2003
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From: Van Steel Corvettes
St. Jude Donor '12-'13
Again, fuel pressure checks out OK. I can also hear the fuel pump just fine. I KNOW I don't have spark, as I've used a spark test light and nothing is getting to the spark plugs. I "think" the coil is firing, but haven't checked it since she's last been out of service. That'll be my next check once it quits raining so much.
Thread Starter
Le Mans Master
Joined: Dec 2003
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From: Van Steel Corvettes
St. Jude Donor '12-'13
I do have a scan tool via my iphone (goPoint). All the data seemed to run smooth when she was running, but I mainly just use it for ready code errors on the vette and my wifes car. My vette mechanic mentioned that too and last time she died, I gave the ECM a nice pop on the top, then the damn vats kicked in. That was fun. Haven't tried it since...may have to when I get home tonight. I think I'd actually rather it be the ECM than the damn opti again...just for the sake it'd be the third stinking one in 8 years. And I've got a vented opti, so it shouldn't do this crap (if it's indeed the opti). But still no codes.
Thread Starter
Le Mans Master
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From: Van Steel Corvettes
St. Jude Donor '12-'13
Well, I pulled the wiring harness to the opti this weekend. It's COVERED in oil. Cleaned it off, plugged it back in and it fired right up. What sucks is I just had the seal replaced a year ago. I had a pro do it with the proper tools and used a GM seal. Another local shop I visited recently has had the same issue with a 96. It's on it's fourth seal in just a couple of months. They too are using GM units (although don't know if they've tried anything else since the first couple went). Any other brands that y'all have used for the seal behind the opti??
Last edited by shakedown067; Sep 4, 2012 at 11:54 AM.
Drifting
Joined: Nov 2002
Posts: 1,365
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From: Huntsville AL
Maybe a bad batch of seals? Normally I would have suspected the mechanic rolled the seal edge by not using the right tool putting it in, but you said he used the proper tool.
Sure it's coming from that seal and not something above it?
Sure it's coming from that seal and not something above it?
Thread Starter
Le Mans Master
Joined: Dec 2003
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From: Van Steel Corvettes
St. Jude Donor '12-'13
Not 100%, but I had everything on the front of the engine replaced at the same time. So it's still a new seal that's let loose. I don't seem to have much oil anywhere else, but if I have to order new seals rather than my mechanic, I'll get them both. Most likely he'll tear into it and then order what needs to be replaced. Just curious on what brands other's have used. Should probably start another thread....
Safety Car
Joined: Sep 2010
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From: Indiana PA
Ask him if he is putting Trans Gel or Trans Assy. Lube on the inside of the seal where the garder spring is. I ALWAYS do this as it helps to keep it in place when installing.
Also, if things are worn, the shaft could be walking around and taking out the seals.
Also, if things are worn, the shaft could be walking around and taking out the seals.
Thread Starter
Le Mans Master
Joined: Dec 2003
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From: Van Steel Corvettes
St. Jude Donor '12-'13
Drifting
Joined: Nov 2002
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From: Huntsville AL
In another thread I had recently about my new AC Delco China water pump, someone advised me to check for wobble (runout) on the splined drive shaft of the pump. If that thing is not straight, it can make the drive shaft in the timing cover wobble around too, which will wear out the seal quickly. This guy had a persistent oil leak from the timing cover that they just could not fix, until they found the runout present in the water pump drive shaft.
Food for thought.
Food for thought.
Thread Starter
Le Mans Master
Joined: Dec 2003
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From: Van Steel Corvettes
St. Jude Donor '12-'13
Well, that would actually be good news. But would the oil leak into the opti? The harness going into the opti at the bottom was covered in oil. Wiped it off, and it fired right up...or was that just from me plugging and unplugging the opti. I'm worried I've still got more than one issue going on.
Last edited by shakedown067; Sep 5, 2012 at 05:36 PM.
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
Well, that would actually be good news. But would the oil leak into the opti? The harness going into the opti at the bottom was covered in oil. Wiped it off, and it fired right up...or was that just from me plugging and unplugging the opti. I'm worried I've still got more than one issue going on.
Drifting
Joined: Nov 2002
Posts: 1,365
Likes: 3
From: Huntsville AL
Well, that would actually be good news. But would the oil leak into the opti? The harness going into the opti at the bottom was covered in oil. Wiped it off, and it fired right up...or was that just from me plugging and unplugging the opti. I'm worried I've still got more than one issue going on.
Thread Starter
Le Mans Master
Joined: Dec 2003
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From: Van Steel Corvettes
St. Jude Donor '12-'13
So got brave and drove it to work yesterday as she's been firing up at will each morning and evening the past few days. Yep, it's now stranded at work. Drove great to work. Didn't go out for lunch, and when I went to go home...no start. Will be kinda nice having it out of the driveway for a while though. Maybe I'll get to tend to it in October. 