Losing all spark
Thread Starter
Advanced
Joined: Mar 2014
Posts: 97
Likes: 3
From: Faith North Carolina
Losing all spark
I have a 71 LS5. I've had it for about a year and a half and this is a recent problem.
While running or driving the engine will just die. It seems to lose all spark momentarily. If I am actually driving it will just buck and keep running. I have had it do it while idling and it goes to die and then picks back up and runs. I have also more recently had it lose all spark for more than 2 or 3 seconds causing a back fire when it starts running again. It can happen just after it starts up and it can happen after it's been running a while. There doesn't seem to be any pattern to it. Also, the car does not lose power to anything else. Lights, etc keep working.
It has an MSD Pro Billet distributor and an MSD 6A ignition box. I have let it sit and idle while tapping around on the various ignition components. I also moved around all the wire tugging on connectors and could not make it die.
It doesn't seem to be a loose connector or wiring being shorted out on anything. Cap and rotor seem be good.
I'm at a loss. Could it be the coil going bad? The 6A box? It is for sure something that causes all spark to go away at the same time.
I'm open to suggestions.
Doug
While running or driving the engine will just die. It seems to lose all spark momentarily. If I am actually driving it will just buck and keep running. I have had it do it while idling and it goes to die and then picks back up and runs. I have also more recently had it lose all spark for more than 2 or 3 seconds causing a back fire when it starts running again. It can happen just after it starts up and it can happen after it's been running a while. There doesn't seem to be any pattern to it. Also, the car does not lose power to anything else. Lights, etc keep working.
It has an MSD Pro Billet distributor and an MSD 6A ignition box. I have let it sit and idle while tapping around on the various ignition components. I also moved around all the wire tugging on connectors and could not make it die.
It doesn't seem to be a loose connector or wiring being shorted out on anything. Cap and rotor seem be good.
I'm at a loss. Could it be the coil going bad? The 6A box? It is for sure something that causes all spark to go away at the same time.
I'm open to suggestions.
Doug
2026 Loser of the Year
Joined: Sep 2013
Posts: 36,597
Likes: 7,046
From: New Or-leens Loo-z-anna
A couple members including me are have similar problems. My problem progressed like yours.
I checked for correct voltage using my 40 year old multimeter at all "important" connections from the alternator/starter/horn relay/fuse block/distributor/cigarette lighter/battery with the key on and also with the engine running....all connections showed 12.6 to 13.9 volts.
then I bought a digital multimeter at the suggestion of forum members because it is more sensitive than my needle-type meter......
The distributor individual internal electronics all tested O.K.
With the engine idling, I immediately found rapid large voltage fluctuations at the fuse block/cigarette lighter/distributor connection even though the engine idles perfectly, BUT any increase in rpm causes the voltage to jump down to 2 volts/the engine backfires and sputters making me suspect the engine wiring harness is finally failing along the firewall or where it enters the fuse block at the firewall.
This may not be your problem/just something you might want to check.
https://www.corvetteforum.com/forums...ackfiring.html
https://www.corvetteforum.com/forums...e-driving.html
https://www.corvetteforum.com/forums...e-popping.html
I checked for correct voltage using my 40 year old multimeter at all "important" connections from the alternator/starter/horn relay/fuse block/distributor/cigarette lighter/battery with the key on and also with the engine running....all connections showed 12.6 to 13.9 volts.
then I bought a digital multimeter at the suggestion of forum members because it is more sensitive than my needle-type meter......
The distributor individual internal electronics all tested O.K.
With the engine idling, I immediately found rapid large voltage fluctuations at the fuse block/cigarette lighter/distributor connection even though the engine idles perfectly, BUT any increase in rpm causes the voltage to jump down to 2 volts/the engine backfires and sputters making me suspect the engine wiring harness is finally failing along the firewall or where it enters the fuse block at the firewall.
This may not be your problem/just something you might want to check.
https://www.corvetteforum.com/forums...ackfiring.html
https://www.corvetteforum.com/forums...e-driving.html
https://www.corvetteforum.com/forums...e-popping.html
Last edited by doorgunner; Jul 11, 2015 at 01:56 AM.
Racer
Joined: Jun 2015
Posts: 315
Likes: 20
From: Vasteras, Sweden
I have a 71 LS5. I've had it for about a year and a half and this is a recent problem.
While running or driving the engine will just die. It seems to lose all spark momentarily. If I am actually driving it will just buck and keep running. I have had it do it while idling and it goes to die and then picks back up and runs. I have also more recently had it lose all spark for more than 2 or 3 seconds causing a back fire when it starts running again. It can happen just after it starts up and it can happen after it's been running a while. There doesn't seem to be any pattern to it. Also, the car does not lose power to anything else. Lights, etc keep working.
It has an MSD Pro Billet distributor and an MSD 6A ignition box. I have let it sit and idle while tapping around on the various ignition components. I also moved around all the wire tugging on connectors and could not make it die.
It doesn't seem to be a loose connector or wiring being shorted out on anything. Cap and rotor seem be good.
I'm at a loss. Could it be the coil going bad? The 6A box? It is for sure something that causes all spark to go away at the same time.
I'm open to suggestions.
Doug
While running or driving the engine will just die. It seems to lose all spark momentarily. If I am actually driving it will just buck and keep running. I have had it do it while idling and it goes to die and then picks back up and runs. I have also more recently had it lose all spark for more than 2 or 3 seconds causing a back fire when it starts running again. It can happen just after it starts up and it can happen after it's been running a while. There doesn't seem to be any pattern to it. Also, the car does not lose power to anything else. Lights, etc keep working.
It has an MSD Pro Billet distributor and an MSD 6A ignition box. I have let it sit and idle while tapping around on the various ignition components. I also moved around all the wire tugging on connectors and could not make it die.
It doesn't seem to be a loose connector or wiring being shorted out on anything. Cap and rotor seem be good.
I'm at a loss. Could it be the coil going bad? The 6A box? It is for sure something that causes all spark to go away at the same time.
I'm open to suggestions.
Doug
I have similar issue, but not as bad, when it gets really hot engine starts to misfire at idle, but at throttle it runs perfect, think it is a ignition issue due to bad voltage to coil or somewhat, going to have it checked at autoelectric shop.
Thread Starter
Advanced
Joined: Mar 2014
Posts: 97
Likes: 3
From: Faith North Carolina
I did find an MSD troubleshooting page. http://www.msdperformance.com/msdhelp/
I'll work through those as soon as i have a chance. My issue is the intermittent nature of the problem. I wish it would just go ahead and break so I could find the issue and fix it.
I started the car this morning and it ran perfect. Took it out for a drive with no issues. Pulled back into the garage and just before I shut it down it did it again. Frustrating.
Doug
I'll work through those as soon as i have a chance. My issue is the intermittent nature of the problem. I wish it would just go ahead and break so I could find the issue and fix it.
I started the car this morning and it ran perfect. Took it out for a drive with no issues. Pulled back into the garage and just before I shut it down it did it again. Frustrating.
Doug
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
I have a 71 LS5. I've had it for about a year and a half and this is a recent problem.
While running or driving the engine will just die. It seems to lose all spark momentarily. If I am actually driving it will just buck and keep running. I have had it do it while idling and it goes to die and then picks back up and runs. I have also more recently had it lose all spark for more than 2 or 3 seconds causing a back fire when it starts running again. It can happen just after it starts up and it can happen after it's been running a while. There doesn't seem to be any pattern to it. Also, the car does not lose power to anything else. Lights, etc keep working.
It has an MSD Pro Billet distributor and an MSD 6A ignition box. I have let it sit and idle while tapping around on the various ignition components. I also moved around all the wire tugging on connectors and could not make it die.
It doesn't seem to be a loose connector or wiring being shorted out on anything. Cap and rotor seem be good.
I'm at a loss. Could it be the coil going bad? The 6A box? It is for sure something that causes all spark to go away at the same time.
I'm open to suggestions.
Doug
While running or driving the engine will just die. It seems to lose all spark momentarily. If I am actually driving it will just buck and keep running. I have had it do it while idling and it goes to die and then picks back up and runs. I have also more recently had it lose all spark for more than 2 or 3 seconds causing a back fire when it starts running again. It can happen just after it starts up and it can happen after it's been running a while. There doesn't seem to be any pattern to it. Also, the car does not lose power to anything else. Lights, etc keep working.
It has an MSD Pro Billet distributor and an MSD 6A ignition box. I have let it sit and idle while tapping around on the various ignition components. I also moved around all the wire tugging on connectors and could not make it die.
It doesn't seem to be a loose connector or wiring being shorted out on anything. Cap and rotor seem be good.
I'm at a loss. Could it be the coil going bad? The 6A box? It is for sure something that causes all spark to go away at the same time.
I'm open to suggestions.
Doug
If you are powering the MSD from the IGN terminal on your fuse block the terminal may be going dead because of a bad ignition switch (which feeds that IGN terminal). Try powering the MSD from a different power source and see if the problem goes away.
Safety Car
Joined: Jan 2009
Posts: 4,000
Likes: 299
From: New York
Run direct grounds ALWAYS , nothing comes close to a battery to device ground.. Also look for these for power and ground connections if you have several things you want to ensure got perfect grounds..
http://www.summitracing.com/parts/pr...FcESHwodwqAMjQ
http://www.summitracing.com/parts/pr...FcESHwodwqAMjQ
