Engine cuts out and stalls while driving.
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
Engine cuts out and stalls while driving.
Blown 383 SBC, Annular Mighty Demon 750 Carb with an MSD HEI.
Car idles ok, but as the RPM builds, the motor cuts out completely and stalls. Seems to be independent of throttle position, and only RPM related. Car restarts after stalling.
What is the cause?
Car idles ok, but as the RPM builds, the motor cuts out completely and stalls. Seems to be independent of throttle position, and only RPM related. Car restarts after stalling.
What is the cause?
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
Bowls are full, up to the top line in the sight glass window after stalling. Fuel pressure guage reads 7psi at atmospheric level, increases 1psi per lb of boost. Carb is tuned at 12.5:1 under boost and 14.5:1 light load low rpm cruise.
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
Motor is cutting out at around 2K-3K, light throttle. Fuel pump has kept up in the past with WOT 13lbs of boost runs.
Thread Starter
Melting Slicks
Joined: Sep 2004
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Likes: 3
Melting Slicks
Joined: Feb 2003
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St. Jude Donor '03,'11
A coil can get hot, copper expands and open circuits, but that normally takes a few minutes to cool off for a restart and it probably wouldn't necessarily cut out at the same rpm every time.
And i've not seen a module have a failure mode like that either. Mostly once they fail they're done.
And i've not seen a module have a failure mode like that either. Mostly once they fail they're done.
Last edited by turtlevette; Feb 4, 2010 at 11:46 PM.
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Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
A coil can get hot, copper expands and open circuits, but that normally takes a few minutes to cool off for a restart and it probably wouldn't necessarily cut out at the same rpm every time.
And i've not seen a module have a failure mode like that either. Mostly once they fail they're done.
And i've not seen a module have a failure mode like that either. Mostly once they fail they're done.
Last edited by enkeivette; Feb 5, 2010 at 12:02 AM.
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
Melting Slicks
Joined: Feb 2003
Posts: 3,053
Likes: 4
St. Jude Donor '03,'11
i notice someone is telling you to replace the whole dizzy on the other site.
You can get a module for $20 at autozone to test your MSD unit. If that's not it, you have a spare to carry with.
You can get a module for $20 at autozone to test your MSD unit. If that's not it, you have a spare to carry with.
Melting Slicks
Joined: Feb 2003
Posts: 3,053
Likes: 4
St. Jude Donor '03,'11
It could be a boost issue. That's right about where a centrifugal blower starts building pressure. But you know that. I'd be helpful if you'd look at the boost gauge and tell us if that has some relationship. The pressure is probably preventing gas from entering the bowls because you have a loose feedback hose on your regulator to signal a boost in pressure as the boost increases.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
It could be a boost issue. That's right about where a centrifugal blower starts building pressure. But you know that. I'd be helpful if you'd look at the boost gauge and tell us if that has some relationship. The pressure is probably preventing gas from entering the bowls because you have a loose feedback hose on your regulator to signal a boost in pressure as the boost increases.
how about the rev limiter resistor?? they got a plug in for those later model MSD units I have never owned/messed with one, except very casually, so wonder what happens if the programming resistor is left out??
Melting Slicks
Joined: Feb 2003
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St. Jude Donor '03,'11
Wouldn't that cause the engine to sputter and stumble like MAD, quit firing and then catch as the rpm's fell?? kinda like pulling 1/2 the injectors offline...??
how about the rev limiter resistor?? they got a plug in for those later model MSD units I have never owned/messed with one, except very casually, so wonder what happens if the programming resistor is left out??
how about the rev limiter resistor?? they got a plug in for those later model MSD units I have never owned/messed with one, except very casually, so wonder what happens if the programming resistor is left out??
He has an MSD HEI which is just like a GM HEI with MSD module and coil. The digital module does have a rev limiter. The analog one like i have doesn't.
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
It could be a boost issue. That's right about where a centrifugal blower starts building pressure. But you know that. I'd be helpful if you'd look at the boost gauge and tell us if that has some relationship. The pressure is probably preventing gas from entering the bowls because you have a loose feedback hose on your regulator to signal a boost in pressure as the boost increases.
Last edited by enkeivette; Feb 6, 2010 at 05:39 AM.
Drifting
Joined: Aug 2005
Posts: 1,682
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From: League City TX
Nobody on either site guessed that a plug wire being grounded to the header caused the problem.
And truthfully, if thats all you found, I would be really surprised if that was what caused it.
One shorted wire causes a dead cylinder, not total shut down.
And truthfully, if thats all you found, I would be really surprised if that was what caused it.
One shorted wire causes a dead cylinder, not total shut down.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
