No spark!

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mopar56

mopar56

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Well the kids duster is finally back together I installed a factory style 72 and up ignition system using the diagram shown but I have no spark I installed a 1980 318 from my other sons truck and used his distributor which works fine I used a new orange box and new after market wire harness and single ballast resistor now before anyone says I should use a gm hei system I DON'T put Chevrolet parts on a Dodge, EVER! And I have used Chrysler ignition systems for years and Never had a failure so this is what I'm using but I must have done something wrong during this install I'm sure it's simple I have 12v at positive and negative coil terminals with key on even though my orange box is new I have several others and have tried them all with no effect also I have some spare coils and tried those to but when I hold the coil wire to ground I have no spark what am I missing here? Oh I should add I have NOT bolted the orange box to the fender yet but I did run a jumper ground with aligator clip from the box to ground, maybe that isn't enough? Thanks

20170523_202022.jpg
 
EDIT, I was typing lol...........THE BOX MUST BE GROUNDED!!!!!!

Try this.......turn key to "run" get the coil wire to test for spark or use a plug or test gap on the coil wire. Disconnect the dist. connector, take up the firewall end and tap the exposed connector pin to ground. It should "snap" one spark each time.

Recheck voltage. With key in "run" you should NOT have full battery voltage on coil NEG. Coil should be drawing current. If you are running a resistor, the coil + should be "down" some in voltage from battery, perhaps 9-10 V

Some itme ago I did a thread on testing these...........Nevermind, I made the mistake of hosting the photos at "tinypic" and I see some of them are now gone
 
Last edited:
What Del said, take the coil secondary wire out of the dist cap & hold it 1/4" from ground. seperate the dist pickup 2 wire zigzag connector & drag the male tip of the ECU half of the connector across the intake surface (ground) which will make/break contact & see if the coil wire sparks & this is with the key "on" & with the key held to "start" & for the last one, first pull the yellow wire off of the "ign" terminal on the starter relay to disable the starter (no need to run the batt down, which puts too much voltage into the system when it does start). confirm that the blue/yellow ECU terminal and the coil positive terminal both are getting fire in "run" and in "crank". I think you did this on the coil at least in run. this'd be a start. they both need to be fed in run/crank. ECU needs to be grounded (you did that). the dist pickup needs continuity to the (2) ecu terminals. check reluctor gap. ohm dist pickup. Holler back with any news
 
mopar56 said:
Thanks I do have full voltage at - on coil so what dose that mean?
Click to expand...

I already attempted to explain. Let's imagine you have BREAKER POINTS and not an electronic box. The functional circuit goes

Battery POS...........Ignition switch..........coil resistor.........to coil POS..........through the coil......out at coil NEG.........to distributor points IF CLOSED........and to ground.........back to battery NEG

(Actually current flows the other direction)

If were to measure voltage along this functional circuit, you might see the following, which is cause by CURRENT FLOW

Battery..........12.6

Switch side of ballast........12.5
Coil side of ballast.............10.5
Coil POS...........................10.5
Coil NEG...........................Very low, perhaps 1/2 volt or less

WHY IS THIS? WHY is there quite low voltage at the ballast coil side? Because the coil is DRAWING CURRENT

On the other hand...........if you bump the engine so the points are OPEN, and the coil is NOT now drawing current, you will read BATTERY VOLTAGE, 12.6 clear through to the coil NEG, because there is no current to cause a VOLTAGE DROP

The same thing is true of your ECU. The way "these work" as per normally wired, is that with key on/ engine not running, they "act like" CLOSED BREAKER POINTS

This means that 'all hooked up' and with the box properly grounded, the coil NEG voltage should be very low, perhaps one volt or so. Coil POS should be lower than battery, perhaps 9--11V The "key" side of the ballast should be very close to battery, perhaps 12.2---12.5
 
OK I'm back at it for a bit so with the yellow start wire off the relay for the starter I have 12v at the coil both sides but no voltage at the zig zag plug and no spark of course when tapped to ground I will try a different ecu box
 
Got it! Not sure exactly what I did but may have been a bad coil? It just didn't make sense all conections were good but no spark from the zig zag I swapped out the ecu with a couple good ones but no change then swapped the coil from the msd one to a regular black coil and BAM I had spark! Then flashed right up! Thanks for all the help!
 
good morning, ok so now I have had a good night sleep and time to think about it, is it possible the MSD coil already had an internal resister? and that was the reason it wouldn't start?, oddly enough the reason I never used the black OEM coil in the first place is I thought it would not be as good as the MSD one, I am happy it runs but would feel better if I knew for sure so I may put the MSD one back on in a while just to see.
 
Ok Thanks, I haven't ever used a MSD but always thought they were good? that's why we put it in, oh well, just another learning curve, lol, thanks for all the help and clear descriptions of the current flow it helped a lot.
 

From what you described, sounds like a bad coil.
 
Ok Thanks, I haven't ever used a MSD but always thought they were good?
Click to expand...
In all fairness it is a very good product & on these sites we are presented with problems to solve so we get all the bad news! & I've had several of em go bad (coils & a box, a 6AL iirc)
 
The best darn coil I have ever used is the square top Accell SuperCoil, Mopar pn 4120889.
It's been reliably firing my 367 since about 2002,from idling in traffic to regular trips to over 7000 rpm for something like 120,000 miles. It followed 1 conventional, and 1 E-core. Third pick was a charm.
 
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