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Discussion Starter #1
Never ending battle. . . . been driving my 69 C-10 since restoring and it and has killed for no reason I can think of. 427, Speed deamon 750DP on an edelbrock, mild engine that was built 20 years ago, carb last year. Has about 10k miles. GM HEI Driving at 25 mph it suddenly killed, another day at the stop sign and the 3rd backing up in the driveway. It started all 3 times with a good bit of time, thought the battery would run out. It like it runs out of gas. See if your thoughts match mine!?
 

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Mike
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ignition module and or coil are likely candidates
Agreed... OP should also confirm that they have 12 volts going the the BAT terminal on the HEI cap (using the correct gauge voltage supply wire).
 

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Discussion Starter #7
GM HEI. . . .doesn't the ignition module just go out and the car won't start or is it sporadic. Wiring harness looks fine. I will check the volts tomorrow. Thanks for all your input guys.
 

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I've had issues with the ignition module a few times. Sometimes it will die without warning and then 20 minutes later it will start up and drive fine for a week, then do it again, won't start, wait a few hours seems as good as new. Both times for me, changing the module fixed the problem. Easy to do, not expensive. I had one GM module fail and one ACCEL fail, so seems to be typical of all modules.
 

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"GM HEI. . . .doesn't the ignition module just go out and the car won't start or is it sporadic"

NOPE, that is NOT accurate, actually, the HEI module is one tough, reliable ignition processor. They do not "just fail for no reason", NOTHING just fails for no reason.

Two areas I would look at, first, the main reason HEI modules fail, THE COIL IN THE CAP going bad, but that usually causes module death as the coil is going bad. To properly test the coil, emove it from the distributor, run it on an off vehicle electrical tester, let it get hot, up to operating temperature, that is where they have the most failure issues. Second, another failure area, the magnetic pickup to module two wire conector. These connectors hold both pickup wires into the HEI module. There have been more than a few wire end terminals in those conectors that were not crimped correctly, cuting a significant amount of the wire strands for both wires. As the pickup moves as the vacuum advance moves it, there is a change that after some miles, the remaining wire strands have disconected, but still butt up against each other, until the pickup is moved by the vacuum advance, then come back together when the advance goes back to rest. To test, use a hand held vacuum pump on the vacuum advance feed hose, with the engine running at idle, operate the vacuum advance. If the engine stays running, look elsewhere, if it stops, then easily restarts when vacuum is removed from the hose, look at the pickup wires inside the two wire connector at the HEI module.

There are many other reasons, but, these two are the most problem prone.
 

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OP

Certainly test and inspect your wiring and the VDC to your distributor to confirm it is 12vdc

...but what you describe, assuming the above notes are confirmed good, is coil and or ignition module.

If it were my car I would buy a new module & coil
 

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When it dies. You say it takes a while to start. Is it flooded? Maybe a bad needle and seat. Is is vapor lock? Bad fuel pump? Dirty fuel filter.

Is it heat related and starts when it cools down.

Could be ignition but could also be fuel issues.

If you cranking a while my guess is flooded but just a guess.
 

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Vapor lock
Bad ground or positive wire/s
Fuel filter clogged
Collapsed fuel line

Would be my guesses and in that order....Happy hunting :beers:
 

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"If it were my car I would buy a new module & coil"

I will reiterate, BEFORE you waste any money on components,

If the engine runs, start it and add vacuum to the vacuum advance hose, if the engine stops, replace the magnetic pickup

Then, take the coil off the car, find an off vehicle electrical tester, run the coil, get it to full operating temperature, and see if the coil is going bad FIRST. If so, do the coil.

Test the module separately, on the electrical tester

Replace whatever has problems.

Battery ground cable to the ENGINE, everything else ground off the engine.
 

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I had a Corvette I fixed that would die after being driven at 65 MPH for 25 miles. Let it cool down and would start right back up. It had previously had everything but the module replaced in the ignition. The module fixed it.

Bought a car that I could drive about 6 blocks and then it would die. let it sit 15 minutes and start and drive another 6 blocks. Clogged sock in the fuel tank.

Jeff
 

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Discussion Starter #15
Fuel line is clean as is the filter. The GM HEI is from the 80's and was never rebuilt when I looked at my notes from way back when. I have ordered a complete ACCEL distributer instead of individual components. The temp had no bearing on the starting function, always ran cool even when towing my Camaros with the AC on. Carb does not flood when restarting, just keeps turning over then kicks in. I really appreciate all the feed back,
 

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Before guessing and spending good money after bad.
When it dies and will not restart..... you have to narrow down the issue
Do you have spark that will jump a 1/4" gap at the dist. cap? no, then fix ignition
Do you have fuel in the carb? no, then look at fuel supply
 

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NOT engine temperature, but under cap module and n cap coil temperatures, can be high enough to cause a coil failure which can cause a module failure, which would result in needing BOTH coil and module.

Pickup wires can deceive, that is why the vacuum test on the vacuum advance, see if the engine stays running, or dies is vital in testing the large coil in cap HEI.

Test before throwing hard earned money at it, fix it right, the first time.
 

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NOT engine temperature, but under cap module and n cap coil temperatures, can be high enough to cause a coil failure which can cause a module failure, which would result in needing BOTH coil and module.

Pickup wires can deceive, that is why the vacuum test on the vacuum advance, see if the engine stays running, or dies is vital in testing the large coil in cap HEI.

Test before throwing hard earned money at it, fix it right, the first time.
X2. If you change module and coil is bad it will fry the module. Your logical conclusion will be the coil is bad because you have a new module. Next you replace the coil and still have a problem because the bad coil ruined the new module.

Down the rabbit hole you go now because you believe you have a new coil and new module so you’re then thinking must be something else.

Maybe replace both coil and module at the same time?
 

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OP

Certainly test and inspect your wiring and the VDC to your distributor to confirm it is 12vdc

...but what you describe, assuming the above notes are confirmed good, is coil and or ignition module.

If it were my car I would buy a new module & coil
X2. If you change module and coil is bad it will fry the module. Your logical conclusion will be the coil is bad because you have a new module. Next you replace the coil and still have a problem because the bad coil ruined the new module.

Down the rabbit hole you go now because you believe you have a new coil and new module so you’re then thinking must be something else.

Maybe replace both coil and module at the same time?
which is why I advised replacing both after some basic testing. Coil fail can certainly take out module so replacing a module but still having a bad coil, as you note, will kill the new module...and yes the rabbit hole gets deeper

OP has said he is buying a new Dizzy...ideally that resolves his issue and he reports results one way or the other
 

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Testing both, OFF THE VEHICLE, is why I suggested it. Old resistance vaunes are only "do-able: COLD, not where the problems are, HOT.

Old world tests are fine, if you and the vehicle are 100 years old, and have decades to resolve problems, 21st century methods work far better in testing tings that cause sayings like "That module/coil failed FOR NO APPARENT REASON". Failures never happen for no apparent reason.

Why would a "new" distributor fix any failure issues? Ever heard of "NEW - DEFECTIVE". Happens a lot more than people see, and believe.
 
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