so my wagon died....

After sitting for almost two months I had just gotten the new flooring in. We were going to take it on a road trip to Tennessee. I drove it to work but on the way home it just died. I was behind a semi and wanted to pass but when I put my foot down it was like it just bogged out. Then shortly there after it died.

after letting it sit for a week I just did some diagnosis on it and I am somewhat perplexed. It cranks over fine with no odd noises or anything. It has spark (at least the number 1 plugwire). I pulled out the oil fill tube and watched at least one valve open and close. I pulled out home plate and sprayed either in the engine with the throttle open. Nothing not a bang, pop, or anything.

IMO it should have done something on starting fluid. I try to not be too heavy handed with the stuff though.

Any thoughts?

Fuel Pump....check the fuel pressure.

You forgot to mention the good news.............you still have the Corvette to drive.


Tom

Did you listen for the pump to prime? Put a pressure gauge on the fuel rail, and check for pressure.

Fuel pressure check is easy on an LT1, have somebody turn the key on while you push the plunger in on the schrader valve on the fuel rail,. IF the pump is making god pressure,. you should have a pretty healthy squirt of fuel come out,.( normal caution here, no smoking,. keep your eyes away from things etc,. etc,.)

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I don't have a fuel pressure gauge, but it would be easy enough to check a schrader valve.

As far as ignition problems, I do have consistent spark, not necessarily properly timed spark, but spark.

Fuel pressure gauges are really cheap...about $15.

I didn't have any time to really get into it but with home base off it was easy enough to find the schrader valve. I cranked it and then checked and fuel sprayed out. I had my son crank it and fuel still sprayed.

I also tried more starting fluid to no avail.

The coil or ignition module may be your issue. Try the ignition module first. You need electronic heat sink compound not dielectric grease when installing the module.

Fred Kiehl wrote:

The coil or ignition module may be your issue. Try the ignition module first. You need electronic heat sink compound not dielectric grease when installing the module.

Please forgive my total ignorance, but If I am getting consistent spark. shouldn't I get something trying to start it on starting fluid? Even if it was improperly timed spark I would think it would back fire or something. I may Be totally wrong but I would think if an ignition module or say a crank position sensor went bad it would not have any spark?

atlantadan wrote:

Edit: VATS problem?

Vats is simply a starter interrupt system,.

VATS is not simply a starter interrupt system.
It has two functions:
1/ When working, it allows the starter to activate.
2/ When working, it allows fuel flow to continue beyond 4-5 seconds.

If it fails, or you use the wrong key, the starter portion of the circuit can be jumpered or bypassed but the engine will only run a very short time before fuel flow is "cut-off". Since the module (under the dash) sends a digital pulse to the ECM to authorize fuel flow, it's a difficult system to troubleshoot or repair. The 9C1's and possibly a few other GM vehicles use a VATS "eliminator" module that sends this digital signal to the ECM whenever the ignition switch is on.

paart wrote:

VATS is not simply a starter interrupt system.
It has two functions:
1/ When working, it allows the starter to activate.
2/ When working, it allows fuel flow to continue beyond 4-5 seconds.

If it fails, or you use the wrong key, the starter portion of the circuit can be jumpered or bypassed but the engine will only run a very short time before fuel flow is "cut-off". Since the module (under the dash) sends a digital pulse to the ECM to authorize fuel flow, it's a difficult system to troubleshoot or repair. The 9C1's and possibly a few other GM vehicles use a VATS "eliminator" module that sends this digital signal to the ECM whenever the ignition switch is on.

mostly true,.

but his car died while driving,. so i used a simple explanation regarding vats,.which in this case is definitely not the problem,.once the ecm is commanded to turn on the fuel flow, it says on till the next ko cycle.

I agree that I have no idea where the spark is happening in the 4 stroke cycle. I will defer to the expertise of the board members on this. Where is the ICM located on our LT1 cars? Is it underneath the distributor cap like on an old SBC?

there are 4 different ICMs listed on rock auto priced from $45 to $115. The AC Delco’s are $90 and $115.
the standard one is cheap, and in the old days standard blue streak stuff was good stuff. Today it seems like you have to guess which part made in which china factory is the best.
any thoughts on what brand?

finally, they list an AC Delco heat sink, I believe this was mentioned before, normally a heat sink is just a big chunk of aluminum, but is this something that can actually go bad? Its only $12.

on the drivers front cylinder head is the coil and icm,. there's a mess of ground wires there too that need to be clean and tight

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Consistent spark is not the same as a good spark. It could be consistently bad.
If the spark is yellowish or orange, that's a bad spark. It should be a bluish white.

Having not seen the "heat sink" you are referring to, I don't want to throw you of the trail.

Is it possible they are not mentioning a metal part , but actually a heat transfer paste that instructions often refer to. It helps the heat pass from one surface to another. The paste can be found at Radio Shack in a little tube, the size of superglue.

lakeffect wrote:

Consistent spark is not the same as a good spark. It could be consistently bad.
If the spark is yellowish or orange, that's a bad spark. It should be a bluish white.

Having not seen the "heat sink" you are referring to, I don't want to throw you of the trail.

Is it possible they are not mentioning a metal part , but actually a heat transfer paste that instructions often  refer to. It helps the heat pass from one surface to another. The paste can be found at Radio Shack in a little tube, the size of superglue.

yes, I agree that it can be "bad spark" or "improperly timed" I only used the term consistent in that it was at the same intervals while cranking. for the most part it appeared blue, but honestly given the daylight I can't say for sure. the "heat sink" mentioned does indeed look like a finned aluminum chunk of metal.

I will invest in an ICM and go from there. I will see if one is available locally tomorrow for a reasonable price, otherwise I will have to wait. this would be a great time to own a "parts wagon".

Along with some parts for my vette my BFF brought me a tube of the thermal compound for putting on the heat sink when mounting the ICM. Rockauto said I should have it by Tuesday.
I hope this is all I need.

No joy with the ICM #$%&!@!

upon more diagnosis while I am still getting spark, I did notice that the first time I tested it seemed like I had a great spark and then the spark would diminish.

My guess is to throw a coil at it, wish I would have bought it at the same time

I went to put my coil on last night. broke 2 of the 3 ground connectors on the bolt for the coil. I really don't understand why they would have 3 separate wire in to 3 flimsy connectors. why not terminate them together into something more substantial? I don't have any eye connectors big enough so I will have to see what the auto parts store has.

OK really starting to get perturbed with the wagon. I finally got time to finish putting the new coil on. said a prayer, it hiccupped a few times but it finally started. it would run for about 3-4 seconds and die.

I will check for fuel in the fuel rail. maybe I am losing pressure?
another thought is the "pass key" light stays on for longer than I think it should. I believe there is some stupid procedure for the key to relearn. something like leaving the ignition on for 10 minutes then trying to start, and repeating three times.

Any more thoughts on this would be greatly appreciated! THANKS!

Passkey will not shut down a running engine. Fuel pressure is important to check. The fuel pump driver might not be "sealing in" when oil pressure is supposed to be detected.

I have had to do a passkey relearn when swapping a steering column, it will start, run for a few seconds and shut off. This was on an OBD-II car, but I could see it being possible here too.

As mentioned above, the PASS-Key II system has two parts: the first part allows or locks out the starter relay, and the second part sends a digital signal to the PCM which then closes the fuel pump relay, powering the pump. The starter relay is easily bypassed, and I’m guessing this troublesome circuit is often bypassed, probably, originally by some dealers.

When the starter relay lockout is bypassed, this has no effect of the other part of the circuit which controls the power to the fuel pump. The “Theft Deterrent Module” (under the dash), reads the resistance of the pellet in the ignition key, via two wires that are run through the steering column to the key switch. This module will always send the digital signal to the PCM for 2-3 seconds to allow the fuel pump to run, but will then stop the digital signal if the resistance in the key pellet doesn’t match the pre-programmed value in the Theft Deterrent Module. Of course, if the resistance matches, the fuel pump relay remains latched, and the engine runs. Additionally, after oil pressure builds to normal, an oil pressure sensor (separate from the “regular” oil pressure sensor) closes its electrical switch in parallel with the fuel pump relay, so that if the relay fails or becomes intermittent, the fuel pump will continue to deliver fuel to the engine.

To test the fuel pump by bypassing this whole nightmare, GM has supposedly included a test circuit, consisting of a “pigtail” wired almost directly to the fuel pump. This is supposed to be located near the underhood fuse and relay box, but is mis-identified in the FSM. I found a loose pigtail closer to the AC dryer than the fusebox, but didn’t try to use it. If you find this pigtail, applying 12Volts to it should cause the fuel pump to run at any time.
A way to check if you have found the correct pigtail would be to remove the fuel pump relay and check for continuity between the pigtail and the center connector of the relay socket (on the side that has three positions). This center connector is connected to the test pigtail, but the relay must be inserted for the pump to run since it’s connected to the “normally open” contact of the relay.

I’m not aware of any “re-learning” capabilities of this system. If a new Theft Deterrent Module is installed, it will read the key resistance one time and retain that value, from that point on.

So it sat for a while and when I got back to it, it started right up????

I ran it up to temp and shut it down. I did not have time to road test it.

Started it up again today and ran it up to temp.

I had my truck out and tonight I wanted to test it with the wife following in the truck with some tow straps. I made it less than 2 miles down the road and it just died.

guess I will check fuel pressure

usuaully the fuel pump just goes, but then again it may be sporadic. your sig file says 145K and I've lost OE fuel pumps from 150K to 180K, so you are right there.

As big a deal as everyone makes about swapping them out, it's not horrible, just time consuming...
if your rail won't hold consistent pressure at 40psi or above (get the gauge for the Schraeder valve, they are alot cheaper than throwing parts at it.

tank drop write up here: [You must be registered and logged in to see this link.]

Sprocket wrote:

usuaully the fuel pump just goes, but then again it may be sporadic.  your sig file says 145K and I've lost OE fuel pumps from 150K to 180K, so you are right there.

As big a deal as everyone makes about swapping them out, it's not horrible, just time consuming...
if your rail won't hold consistent pressure at 40psi or above (get the gauge for the Schraeder valve, they are alot cheaper than throwing parts at it.

tank drop write up here:  https://gmlongroof.4umer.com/t1426-write-up-on-how-to-drop-your-tank

I'm at 160K right now. I am hoping to run into the big city tonight for something and I will buy a fuel pressure kit at harbor freight if I go. I don't want to throw parts at either, but it is weird how it just cut right out an died.
I don't care about dropping the tank, I have a hoist and underhoist jackstands and the car is immaculate underneath. I just want to fix the freekin thing.

right now the wife's car is on the hoist and I am putting a trans in it.

So my trip to the big city last night allowed me to purchase a fuel injection test kit. Hopefully I will have time this weekend to see if that is the problem.