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?
 

RemCharger

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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
 

71Newp

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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.
 

1970FuryConv

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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?
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
 

1970FuryConv

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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.
 
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I had this same problem and it was the gap in the distributor from the rotor to the pickup. Needs to be very close.
 

1970FuryConv

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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.
 

carguy300

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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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