cant figure this ignition problem out

[benno440]

Hi I have a 68 charger with a big block it has msd 6 al ignition, msd blaster 2 copil and pro billet distributor. car also has had a full rewire 2 years ago with a orn francais kit with fuse box, so ballast resistor is no longer there. car has been driving well then all of a sudden it wont start, I checked spark plugs and there not getting a spark, so I put a multimeter on power side of coil with ignition on and there is no power, there is also no power at distributor plug, tried to do a resistance test on coil and when checking both terminals together there is nothing, but when negative is on the main plug and positive on the positive terminal it reads something crazy like 571 on the multimeter. what would you think could be my problem here or where to start looking?

I am stumped

 

[383man]

Well MSD systems will not have any voltage reading showing at the coil positive terminal with the key on eng not running as its a CD ign and wont power the coil until the eng cranks. But if you put an ohmeter across the coil primary + and - terminals you should get in the area of about 1 ohm. On most coils if you go from either primary terminal to the coil center (the output spark to the plugs) you should get in the area of about 8 to 12K. Are you sure you had the ohmeter on the right scale. Also on most systems you wont have any voltage at the dist plug as it should use an AC type magnetic pick-up which you can ckeck for an open with the ohmeter. Most Mopar AC dist pick-ups read about 300 to 900 ohms . If the pick-up reads an open circuit its bad. If you have no continuity (open circuit) across the coil primary + and - neg then yes the coil is bad. Ron

 

[beezee]

Confirm 12v @ the heavy black and red wire,the keyed 12V red wire.Disconnect the distributor plug. Hold the coil wire 1/2" off of a good ground .Take the white MSD wire and rapid touching on and off a negative ground source will create spark if the coil ,coilwire and MSD is good.

 

[benno440]

thanks guys, I did not know that Ron thanks.
My guessing is bad coil then

- - - Updated - - -

Ron,

See pics, I believe I have the multimeter setting on the right one, the OHM selector, it is showing nothing between the 2 terminals but when neg is on main plug and pos is on the pos terminal it shows 5653 ohms.
would this be a faulty coil?

 

[HT413]

I had a similar issue with a procomp ignition that came on my car. Suddenly wouldn't start and when I used an voltmeter across ignition output and coil output, nothing. Problem is in AC mode, a voltmeter can only read sinosoidal waves. In DC, a constant linear voltage. MSD type ignitions put out a different wave form, therefore standard voltmeters cannot detect them accurately.

So it could be the box, could be the coil. Only sure way is to replace the coil first as it's cheaper.

 

[benno440]

thanks

 

[383man]

There are other test you can do to check it out but if you have an open across the coil primary terminals which it looks like you do then the coil is bad. The 5653 ohms is the secondary winding which is a little lower then I usually see but it looks like the primary winding is open in the coil. Ron

 

[coloradodave]

From MSD's site:
MSD IGNITION • WWW.MSDIGNITION.COM • ( 9 1 5 ) 8 5 7 - 5 2 0 0 • FA X ( 9 1 5 ) 8 5 7 - 3 3 4 4

CHECKING FOR SPARK:

If triggering with the Magnetic Pickup:
1. Make sure the ignition switch is in the “Off” position.
2. Remove the coil wire from the distributor cap and
set the terminal approximately 1/2" from ground.
3. Disconnect the MSD magnetic pickup wires from
the distributor.
4. Turn the ignition to the On position. Do not crank
the engine.
5. With a small jumper wire, short the MSD’s Green
and Violet magnetic pickup wires together several
times. Each time you break this short, a spark
should jump from the coil wire to ground. If spark
is present, the ignition is working properly. If there
is no spark skip to step 6.
6. If there is no spark:
A. Inspect all of the wiring.
B. Substitute another coil and repeat the test. If there is now spark, the coil is at fault.
C. If there is still no spark, check to make sure there are 12 volts on the small Red wire from the
MSD when the key is in the On position. If 12 volts are not present, find another switched 12
volt source and repeat the test.
D. If, after following the test procedures and inspecting all of the wiring, there is still no spark, the
MSD Ignition is in need of repair. See the Warranty and Service section for information.

 

[benno440]

thanks Dave, did not even occur to me to check that out,
I did a quick check on the power to the coil while engine cranking and still got no power, I made a mistake in original comment as I do still have a ballast resistor on the car, my bad

 

[benno440]

okay did a few MSD tests.

* disconnected coil lead at dizzy and sat it 1/2" to ground and then put a short wire in the magnetic pickup wire with ignition on, it says if you get a spark from lead to ground everything in fine, but I am not getting a spark but I can hear the msd ignition clicking when I do it.
* tried an OHM test between pos and neg on coil it says you should get a reading of about 1.2 ohms roughly and I get nothing.
* tried an ohm test of magnetic pickup points and I get nothing.

whats your thoughts? stuffed coil? stuffed ignition box maybe, I will order a new coil and see what happens.

 

[SlinktRR]

benno, make sure to use alligator clips between the probes of the multimeter and the terminals on the coil. If you don't, it will be very difficult to get a steady accurate reading.