71 Cuda 340 engine stops / will run if holding key in start position.

Author Topic: 71 Cuda 340 engine stops / will run if holding key in start position.  (Read 900 times)

Offline woody9512

  • Jr. Member
  • **
  • Posts: 264
  • 71 Billboard Cuda, Pistol Grip 4-speed.
Have 71 Cuda and can't safely drive it :feedback:
 I have a problem I will describe and now onto my picking everyone's Mopar brain. Last spring I took car out of storage started it up and was idling great and it just stopped like the snap of a finger. Tried to start it but strange thing is the engine would only run as long as I held the key in the forward start position?? Soon as I let go of key engine stopped. Even stranger If I left the car sit for a bit (cool off) it will start right up, engine runs for while, then will do the same thing and stop?? Hold key forward in start position and engine with continue to run. Let go of key engine will stop. That being said I didn't drive it last year as don't want it to just stall in traffic. I'm wondering with all your knowledge if you have an idea what the problem might be or if you know of anyone I can run the issue by for and educated guess? If I needed to eventually trailer it to someone that wouldn't be an issue if you know of anyone in the London, Ontario general area who is good at solving this kind of stuff? Mechanics that work on these older cars are getting fewer and fewer sadly. I tried replacing the ceramic ballast resister on fire wall hoping that was it but did same thing so not it? I have people tell me, replace ignition switch ( that was done about 2 years ago when I has all the car's wiring , guages, interior redone by a well known Mopar restorer in Milton area but could new switch one installed be now bad? I ran it by the guy who did the work and he had no idea as to what my problem might be. Some say replace ignition key cylinder?? Lots of ideas out there but thought I would run it by you guys here since you have worked on so many of these cars and or maybe know someone I can run this problem by. Would certainly like to get driving it again that's for sure but can't safely do it now and don't want to stall in traffic.

Thanks Again and Happy St Patrick's Day Tim




Offline Oldschool

  • Administrator
  • Permanent Resident
  • *****
  • Posts: 13195
  • Member Since 9-05-06
Re: 71 Cuda 340 engine stops / will run if holding key in start position.
« Reply #1 on: March 17, 2023 - 05:00:21 PM »
I would start with replacing the ignition switch first. It seems by what you are saying that the issue is centered around the switch itself. That is a fairly inexpensive way to eliminate one possible cause. 0.02... :2thumbs:
Ken  --  In Georgia

MOPAR-------"Built To Run------Here To Stay"

Offline woody9512

  • Jr. Member
  • **
  • Posts: 264
  • 71 Billboard Cuda, Pistol Grip 4-speed.
Re: 71 Cuda 340 engine stops / will run if holding key in start position.
« Reply #2 on: March 18, 2023 - 09:18:28 AM »
Thanks for the reply.
Had ignition switch replaced about 2 years ago but maybe the new one I put in is bad.
Tim

Offline 'Cuda Hunter

  • Sr. Resident
  • ******
  • Posts: 9102
  • Tastes Like Chicken
Re: 71 Cuda 340 engine stops / will run if holding key in start position.
« Reply #3 on: March 18, 2023 - 10:50:02 AM »
I agree with replacing the ignition switch. 
"All riches begin as a state of mind and you have complete control of your mind"  -- B. Lee

Offline JayBee

  • Resident
  • *****
  • Posts: 2477
Re: 71 Cuda 340 engine stops / will run if holding key in start position.
« Reply #4 on: March 19, 2023 - 10:19:24 AM »
Are you sure the ballast resistor is good and measures somewhere around .6 ohms. Check for broken wires too, sometimes they split near the crimped terminal. Look for bad connections at the bulkhead connector and at the ignition switch plug down the column. When the key is in the ON position you should have around 7 volts at the coil. Your issue could still be a bad new ignition switch, God knows what crap comes from China.

https://www.youtube.com/watch?v=pWxJmbm5V3s
John

1970 Barracuda convertible
2014 Toyota Avalon

Offline jimynick

  • Resident
  • *****
  • Posts: 4512
Re: 71 Cuda 340 engine stops / will run if holding key in start position.
« Reply #5 on: March 21, 2023 - 09:18:40 PM »
I think Jaybee is right, as the run when on start and not when on run is classic ballast resistor misery. Simple enough to check, just take the spare out of the glovebox and mount it. What? don't have a spare? Somewhat like the 90%+ of Mopar owners do because of that fault? Been there...............  Hope that fixes it for you.  :cheers:

Offline woody9512

  • Jr. Member
  • **
  • Posts: 264
  • 71 Billboard Cuda, Pistol Grip 4-speed.
Re: 71 Cuda 340 engine stops / will run if holding key in start position.
« Reply #6 on: March 22, 2023 - 06:12:22 AM »
I did have a spare ballast resistor and swapped it out but didn’t solve the issue and I had thought of that.