Starting problem

[polarbear123]

I have a starting problem sometimes car starts fine at other time car will turn over and run if I hold key in the cranking position when I let go of key it will stop immediately.

[jimynick]

Well, others know much more than I . but the crank and run circuits are separate and the most likely culprit may be either the ignition switch itself or the bulkhead connector where the run circuit passes through to feed the ballast resistor and coil. It's a place to start at least. Good luck and hopefully more experienced members can add their thoughts.

[polarbear123]

Thanks I was thinking ignition switch too. I replaced that switch 2 years ago when I had turn signal problems

[Chryco Psycho]

Ballast resister can cause this also , tyr swapping that out first

[Bullitt-]

Anywhere there is a connection, bulkhead connector on firewall & the wide flat plug at the steering column are places to check. Check, clean and add dielectric grease.

[polarbear123]

Thanks, I think I found problem bad ground from starter relay

[BLUE CUDA]

How did you ground the Starter Relay?

[Strawdawg]

There is no ground on the starter relay other than the park/neutral interupt switch and that only applies when cranking the car initially.  The starter relay has zero to do with the car running once the key is released from the Start position.

[BLUE CUDA]

So what would cause it not to keep running once the key is released from the start position? My car is an 1970 Cuda with 4- speed.

[Strawdawg]

Believe this has already been stated, but ballast resistor is number one cause.  Then we have the ignition switch, Blue wire from switch  to bulkhead connector, blue wire from bulkhead connector to ballast resistor, and then brown wire from ballast to coil

When you turn the key to Start, power comes out of the ignition switch thru the the brown wire to the bulkhead connector and then comes out under the hood and bypasses the ballast resistor and goes to the coil...that way you get full power to the coil for starting.

When the engine starts and you let off the key back to the Run position, power then comes out of the switch on the blue wire, goes to the bulkhead connector, comes out of the bulkhead connector under the hood and goes to the ballast resistor...then comes out of the resistor and goes to the coil via the brown wire on the other end of the resistor.

usually as I said, the ballast resistor goes bad so the car starts, but when you let off the key to Run, there is a break in the circuit so the power cannot continue to the other side and on to the coil


I would turn the key to Run (On) and go to the ballast resistor and see if there is power at the ballast resistor where the  blue connects.   If there is, I would then check the other end of the resistor and see if you power there (should be more like 7-8 volts instead of 11-12.

If not, change the resistor. 

If you did not have power on the blue wire at the resistor, I would get under the dash and see if you have power at the blue wire where is comes out of the column to the the connector.

[BLUE CUDA]

I changed the ballast resister. still won't start.

[Chryco Psycho]

look for connection problems anywhere in the circuit Strawdog explained , bad bulkhead connection at the firewall or the ign plug at the base of the column are often overlooked

[polarbear123]

Ok I wanted give everybody an update. It turned out to be the blue wire from flat plug at the steering column. I was able to see it arching at the plug when I turned the key. Sometimes it would work sometimes not.

[Strawdawg]

Hope it stays fixed!

[polarbear123]

It will it doesn't go through the plug anymore.