No power while cranking

[Vaultman]

1974 dart 318. Ok, while cranking I have no power to anything until I let go of the ignition out of the cranking position, then it starts sometimes. It usually backfires through the carb as soon as you let go of the ignition. If it does start, runs great but keeps shutting off. Most of the time it don't die completely, just enough for the heater and wipers to lose power and stumbles back to life. Driving it does the same thing, all gauges go to 0, heater stops then instantly goes back to normal. I changed the ballast resistor, ignition module, starter, starter relay, coil, wires, cap and rotor. The car sat in a garage covered up for 32 years. I cleaned the 3 plug ins at the firewall and changed both battery cables. I just ordered an ignition switch and it will be in today. Could the switch be the culprit?

 

[QuickDart360]

I had a similar issue in my dart sport 360. Same symptoms. Another member had advised to pay attention to the female connectors of the ecu plug. Over the years they lose their tension and do not make a tight connection with ignition box. So the solution was to use some needle nose pliers and squeeze the each female connector till it closes the gap running down the side. This actually alleviated my issue of no fire! Maybe try this on your car.

 

[QuickDart360]

I had a similar issue in my dart sport 360. Same symptoms. Another member had advised to pay attention to the female connectors of the ecu plug. Over the years they lose their tension and do not make a tight connection with ignition box. So the solution was to use some needle nose pliers and squeeze the each female connector till it closes the gap running down the side. This actually alleviated my issue of no fire! Maybe try this on your car.

 

[RustyRatRod]

Check the main harness connector at the firewall. Make sure its connections are clean, tight and not melted.

 

[AJ/FormS]

If the wipers are shutting off, this is a power-supply problem, and very likely originates in the Fusible link or the bulkhead disconnect. The latter being most likely.
What's odd tho is that it cranks like normal...........

I want to change my mind to faulty ignition switch.

 

[RedFish]

Reads like possible ignition switch.
Its not that hard to test with a meter but... you already bought one.
The switch sends power out to different wires in different positions. It dont take a whole lot of power to activate the starter relay (yellow wire). Starter itself runs on a different/larger wire.
Low voltage into the ignition switch would prevent other circuits from functioning in other switch positions.
Its not uncommon for manually operated switches to fail eventually. Its not uncommon for this models switch connector to harness connector to overheat and melt either.

 

[67Dart273]

^^See above^^. There are two sources of ignition power FROM the ignition switch. IGN1 "run" IS ONLY HOT in "run." During cranking a special separate contact provides power direct to the coil + side of the ballast resistor--normally brown. This comes from IGN2, and like the start wire is ONLY hot in "crank" but they are actually separate from each other to prevent backfeed problems

Put your light/ meter on the coil+ With key "in run" you should have somewhere around 6--10V. Now crank engine using the key and watch the meter or light. You should not have full battery voltage, and at least 10.5 minimum, depending on battery charge

 

[Vaultman]

I tried to start the car before I tore into the ignition and noticed smoke from around the carb. It was the thing that the choke thermostat plugs into. I unplugged it and car starts great.

 

[67Dart273]

That is the choke delay unit. It likely shorted. You are "darn lucky" you did not melt some wiring, as most of that circuit is not fused

 

[RedFish]

I tried to start the car before I tore into the ignition and noticed smoke from around the carb. It was the thing that the choke thermostat plugs into. I unplugged it and car starts great.View attachment 1715817501

That is electrical choke assist/heater controller. It only helps open the choke a little faster. You dont need it. Choke will still open fully, only a little slower.
Everything electrical that they added in the engine bay along the way was added to the only switched 12 volt wire in there.
I've posted in previous threads that this thing can short and rob power from other components.

 

[Vaultman]

That is electrical choke assist/heater controller. It only helps open the choke a little faster. You dont need it. Choke will still open fully, only a little slower.
Everything electrical that they added in the engine bay along the way was added to the only switched 12 volt wire in there.
I've posted in previous threads that this thing can short and rob power from other components.

It did just that.

 

[RedFish]

The sad part... owners have replaced ignition switches, ignition modules, and more, without first looking for voltage loss, what vein is bleeding. I'm guilty too. My current 67 model had a relay that uses only a signal from blue with white tracer coming from ignition switch to supply everything beyond it with full battery voltage. It takes a good bit of effort to wire one of these classics like new vehicles are wired. The 67 model didn't have that choke heater or anything else added to the contacts of its dash mounted ignition switch before I upgraded to electronic ignition, stereo and amplified subwoofer.
Because I had already seen the white harness connector from a better built column mounted ignition switch overheat and melt, I knew I had better take some load off of the 67 ignition switch I'm using.