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68' RR WONT START

Mstone68440RR

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Local time
10:32 AM
Joined
Jun 14, 2014
Messages
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Location
Escondido, CA
Took my Roadrunner to a cruise last a Thursday evening, all was great until about a half mile to go when the car died.

Did not have any tools to work with but diagnosed no spark from the coil. Thinking I may have a bad coil I had the tow truck driver stop at the closest parts store and tried swapping out the coil with no luck. I finally had some free time to work on it today, no voltage getting to the coil from my MSD 6AL. Called a very knowledgeable Mopar friend and asked his opinion, he said the MSD may have died and to take it out and send to them for testing.

This afternoon, I removed a different MSD 6AL from another car I have sitting beside the house in hopes that that would cure the problem, well I just got done swapping it out and the car still does not start. Checked and still no voltage to the coil. The donor car I swapped the 6AL from has been sitting non op since 2004, so no guarantee that the other ignition was any good either.

Fuel pump is working, jets squirt fuel when accelerator is pressed.............I am confused as to what step to take next?


Any suggestions?

68' RR 440/727 MSD 6AL IGNITION, ballast resistor bypassed (have not touched anything with the wiring since I have owned the car) stock distributor, new cap and rotor about 6 months ago, along with new Taylor 8.2 mm plug wires at the same time. I have had the car for over 3 years and this is the first time I have been stranded. It feels like I am missing something simple?
 
Last edited:
Hey Mark -I’m sure you checked to see if you have a crack in the distributor cap. Wouldn’t that cause the problem? Just guessing - I’m sure someone else will chime in
 
Nothing from coil, so not distributor cap.

LED flashing on msd?
 
Pull dist cap. Inspect wires and connections to msd.
 
Maybe i'm displaying my ignorance. As i"m clueless about msd. But, is there a ballast resistor in line ?
 
Yes the MSD is grounded to the same bolt on the block as the battery.
So 2 msd's one bad and one good.....probably ruled them out

Next is the wiring....good ground, good positive...white wire thats not used is that shielded/covered..

I would inspect all wiring....sounds like a poor connection probably
 
So 2 msd's one bad and one good.....probably ruled them out

Next is the wiring....good ground, good positive...white wire thats not used is that shielded/covered..

I would inspect all wiring....sounds like a poor connection probably


Not necessarily, the second MSD I swapped came from another RR I bought last year that has sat non op since 2004, so no idea if that unit is good either.

I just went through all the wiring and I cannot find anything obvious that is wrong or has a poor connection.
 
I may be way off here. But it couldn't hurt to check this. I had a 70 cuda with ignition trouble once. I found the back side of the casing of the voltage regulator was not grounding to the fire wall.
 
Do you have 12v going to the msd? After 3 yrs I would make sure ur ground is clean also.
 
Did you try messing with the bulk head connectors?. If there's no power at at the coil try jumping it. Run a wire from your battery to your coil. If it starts you Will have to disconnect the wire before it will shut off
 
Did you try messing with the bulk head connectors?. If there's no power at at the coil try jumping it. Run a wire from your battery to your coil. If it starts you Will have to disconnect the wire before it will shut off
check for foul plugs.
 
How did you test for spark?

Also, old stuff off of other cars.....I agree both could be bad....

It is either wiring or the box....my first guesses rule this out and move to other things....
 
My best guess is the box died, since it happened While the car was running........unless a poor connection at the bulkhead finally failed? I will have to look up some schematics and and trace out the wiring and verify everything is intact.
 
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