No spark while cranking?

73 grancoupe

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I'm have problems with not getting a spark while ignition switch is turned to cranking but I will get a spark at run. The car is a 73 fury with tilting steering column so it has the delco style ignition switch. I replaced the switch with a new old stock and still having this issue. But sometimes it will start once I release the key to run after trying to crank it. I took the new switch off the column and notice if I grip it tightly I hear relays turning on and off could the new switch also be bad? Or is it something else?
 
Bad ballast would be where it runs in start, but not run.
Time to Crack out the test light.
Check for power from ignition, to ballast in crank mode
 
This is a classic example of a bad ICM. Either the ICM itself is bad or there is a bad ground. First try cleaning the surface where it attaches to the firewall and if that doesn't work you will need a new ICM.
 
I'm have problems with not getting a spark while ignition switch is turned to cranking but I will get a spark at run. The car is a 73 fury with tilting steering column so it has the delco style ignition switch. I replaced the switch with a new old stock and still having this issue. But sometimes it will start once I release the key to run after trying to crank it. I took the new switch off the column and notice if I grip it tightly I hear relays turning on and off could the new switch also be bad? Or is it something else?
I had the exact same problem with my 1973 Monaco. Tilt column/Delco ignition, everything.
This ECM cured the problem.
for MOPAR HR7500 Electronic Ignition Module Dodge Plymouth Chrysler MAX RELIABLE | eBay
 
Note, when going to the 4-pin ECU, cut the dark green/red wire off the 5-pin connector. 4-pin ECU does not use auxiliary power. Also, you need a single ballast resistor. Second side of dual ballast resistor not needed with 4-pin.
Single ballast resistor
Blue is ignition run, brown is start.
BR2.jpg

5-pin (trash) vs. Rick's 4-pin
PXL_20220204_180736635.jpg

4-pin ECU and single ballast resistor cured the starting problem immediately.
 
I had this same problem and it was the gap in the distributor from the rotor to the pickup. Needs to be very close.
 
If I go with the 4 pin I don't need the duel ballast anymore?
Yes, you use a single ballast resistor like the one pictured.
The second side of the dual ballast resistor regulates aux charge to the ECU. 4-pin does not use aux charge.

For reference on Dual Ballast resistor: computer control auxiliary side: once the circuit passes through the jumper wire at the top of the ballast resistor the current at start goes down through the 5 ohms side, auxiliary side of the ballast resistor to the dark green/red wire that gives power for the ECU to send to the distributor.

Dark green/red wire is 5th pin, unused with 4-pin ECU.
 
I agree with all, I ran 4 pin on my last 300, after installing an upgrade electronic/ solid state wiring harness from Evans, and new starting, charging and running components, never had any issues after that.
 
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