coil/starting problem

[Sjd556]

so Ive run into a weird no spark issue on my 73 383 charger that I originally thought was a bad coil. I cut apart the entire engine wiring harness because the car was originally a 318 that I swapped the bb into, so I could see if I messed up the wiring somewhere along the line. after fixing a few things and re taping the harness I am still having no spark at the coil, but am now getting power to the coil...ok. replaced the coil with a brand new msd, still nothing now it seems like I'm getting a crap ground to the coil from the ECU. switched to another unit I had laying around, same thing. Now it looks like I'm getting ground from one of the prongs on the ecu that is NOT supposed to supply ground. I'm at a total loss... if anyone can chime in that would be great. Also switched in a new ballast resistor. also not getting any crank from the key , been bypassing and cranking just from the starter solenoid.. not sure if this has anything to do with it or not..

 

[Don Frelier]

You likely need to go further back:
Bulkhead connector
Ignition switch
To prove it, disconnect feed side of the ballast resistor and try powering the ballast resistor with a temporary feed and see if it starts.
The starter relay problem could be neutral safety or again bulkhead or ignition.

 

[PurpleBeeper]

Don is giving good advice. With all the changes, you "might" have more than one problem. Take a breath, have a beer, step back. You only need about a half dozen wires for the car to run, so check them one at a time & before you do that, check/clean all your grounds.

 

[Sjd556]

I cut the entire harness apart today to check all the wires and ensure proper connections and placement.. I don't get why I'm getting power to the coil but still no spark when cranking (even if I'm jumping the starter relay.) I'm figuring the no key cranking is from the nss and the trans not being in park, I don't yet have the shifter, cable or driveshaft installed so I have to manually cycle the gears on the trans from underneath.. will take a look at the starter relay tomorrow morning..

probably pertinent details but the car is auto and I just finished the complete driveline swap. 318-727-8 1/4 to 383-727-dana60.. lots of changes to account for but as stated not a ton of wiring.. and going over all the diagrams I've seen, everything is connected to its proper spot.

what do you mean by connecting a "temporary feed"? like + direct from battery? couldn't that damage the coil?

 

[Sjd556]

agreed, lots of changes so lots of potential for issues. my head is spinning with possibilities

 

[Don Frelier]

If it's a mopar electronic ignition, it could also be the reluctor gap or the reluctor itself.
If you still have the 318 distributor you can just set it on the engine, plug it in and spin it with your fingers if it sparks then its in the distributor.
One thing at a time.

 

[Sjd556]

I do still have the small block distributor laying around.. how would one spin it with their fingers with the cap on if its on the engine? id assume the only way you could spin it would be if it wasn't in the engine.. or did you mean just LITERALLY set it on the air cleaner..? if so then I will certainly give that a try.. interesting concept that I didn't think about at all! can you explain a little more about the reluctor gap? is that something to do with the inside of the distributor?

 

[Sjd556]

Okay update. Think I have 2 bad ecu’s because was not getting - out to coil. Bypassed directly from battery, now have + and - going to coil, but still no spark..ok now no power to distributor...bad ecu?

 

[Don Frelier]

I do still have the small block distributor laying around.. how would one spin it with their fingers with the cap on if its on the engine? id assume the only way you could spin it would be if it wasn't in the engine.. or did you mean just LITERALLY set it on the air cleaner..? if so then I will certainly give that a try.. interesting concept that I didn't think about at all! can you explain a little more about the reluctor gap? is that something to do with the inside of the distributor?

Just set it close enough to plug into the engine wiring harness, the two pin plug.
Leave the one you have installed where it is.
Power the ignition and just spin end of the old small block distributor in your hand.
The reluctor gap is the space between the pickup coil it should be about .008" and the reluctor itself which looks like an 8 pronged gear.

If you don't have a feeler gauge about 4 thicknesses of regular paper will be close.

The ECU's these days do seem to have quality problems.
You can check for spark by pulling the coil wire off the distributer and setting it about 1/4" from any clean ground like a bolt.

 

[Sjd556]

Problem found, had a loose splice in the harness that I found after getting angry and just pulling wires and boom...one popped right out. Problem solved, have spark, time for fire up later today! Hopefully that goes without headache..

 

[Sjd556]

this just goes to show always sweat the little stuff, I checked the harness completely, cutting the entire thing open and checking/rerouting every wire. all the while, an old splice that I thought was good, wasn't.

 

[Don Frelier]

If you really need to have a splice, then the best way is to solder and put heat shrink tube over the connection.

 

[WileERobby]

Take a breath, have a beer, step back.

This is "terrible" advice. If you're like me, you'll just have another beer, then another. Then, I 'll either fall asleep or forget what I was doing in the first place
Now... What was the question ?

 

[PurpleBeeper]

This is "terrible" advice. If you're like me, you'll just have another beer, then another. Then, I 'll either fall asleep or forget what I was doing in the first place
Now... What was the question ?

I can't remember....I'm on beer #4

 

[WileERobby]

I can't remember....I'm on beer #4

Let know when you finish, I'll break out another.