Ignition start / run question

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supertruck

supertruck

Unretired Old Fart stock car racer
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Car is a 73 Dart 340 Sport. Trans is a Chevy 200-4R with B&M Megashifter. Engine is just broken in and I'm still in the middle of doing all the normal checks to make sure everything works. Converted the 4 pin ballast to a 2 pin, new Mopar chrome box, new voltage regulator, and new starter relay, new ignition switch. MAD bypass was done, crackedback's headlight upgrade and heavier alternator wiring kits installed.
When cranking, the engine spins as it should but doesn't seem to fire until the point when I release the key and it drops back to RUN. It starts right up then, just when the key begins to move from the START to RUN position. Any suggestions appreciated.
 
Sounds like you don't have "ign1" and "ign2" jumpered together

IGN1 is the "run" ignition line comes from the ignition switch, through the bulkhead, and supplies underhood loads, ignition, VR, alternator field, some smog devices

THIS POWER GOES DEAD during cranking

Orginally, IGN2 came from the switch (usually brown) through the bulkhead, and to the coil+ side of the ballast. THAT IS THE ONLY source of ignition power during cranking

Both IGN2 and the "start" wire are hot during cranking, but the come from different switch contacts.
 
My 73 Duster (unmodified) all stock slant with 3 speed in floor does the same sometimes.not always..................................Jeff
 
Thanks 67Dart273. Always glad when you chime in, you know your electrics. If I check IGN 2 in Start at the ballast I should get voltage, correct? If I don't, what was the comment about jumpering Ign 1 and Ign 2?
 
That can be a sign of a bad ballast resistor.
 
Check the bulkhead connector where the ign hot wires pass.

Simple test, put the key in run, test the side of ballast not connected to coil. No power, bulkhead or switch is a likely culprit. If you have power, test other side of ballast. No power, bad ballast.

Disconnect the starter trigger wire at starter relay so the engine doesn't spin over
Put key in start, the coil side of ballast should have power. If not, check bulkhead wires for power on pass compartment side when in start.
 
supertruck said:
Thanks 67Dart273. Always glad when you chime in, you know your electrics. If I check IGN 2 in Start at the ballast I should get voltage, correct? If I don't, what was the comment about jumpering Ign 1 and Ign 2?
Click to expand...

Actually I screwed that up. With a ballasted system, you do NOT want to interconnect the two. Crackedback is right you need to see if you are getting that voltage from IGN2. Wiring diagram? MyMopar. See if coil+ has voltage during cranking, it likely not
 
That schematic is priceless. Printed mine out and glued it to a long piece of cardboard several months ago. Use it all the time in my project.
 
67Dart273 said:
Actually I screwed that up. With a ballasted system, you do NOT want to interconnect the two. Crackedback is right you need to see if you are getting that voltage from IGN2. Wiring diagram? MyMopar. See if coil+ has voltage during cranking, it likely not
Click to expand...
Coil and ECU need power during start. I suppose if one is hot the other is also but... just never know. Dual ballast was deleted so maybe a current path to ECU was lost?
 
Think I found the problem guys. I kept getting inconsistent continuity readings from the wiring between the ballast and the coil. After removing the wiring loom, I found a bad spot in the wire about 4 inches back from the ballast. Replaced the wire, soldering all connections, and it starts up fine now. Thanks for all the suggestions.
 
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