Help needed with starting problem

[Daniel Flores Jr]

Hi,
I'm new to this forum and new to owning a classic car. I'm having an issue with 1970 roadrunner, engine is 1974 400 bb. When I go to start it, fires right up runs not even a full second the dies instantly. Carb is new and I had it dyno tuned when it was installed. It did this while they were tuning it and said possible ignition switch or tumbler. It stoppped acting up then and has been intermittent issue but would start up, now it's doesn't run. FYI I just installed a new ignition coil and it did run but it's back to doing it again.

(See photo) Also can anyone tell me what this part is? If you notice it seem like something inside of it has melted and is ozzing out. (the honey colored stuff at the bottom)



Thanks for any help it's greatly appreciated!!

 

[Rick62]

A likely suspect would be the ballast resister. If, not the ignition switch may be a possibility.

 

[Dennis H]

Check the Buklhead Connector on drivers side engine compartment firewall for good measure.
Remove each bank carefully and spray with contact cleaner then reinstall.

 

[Shorthorse]

That picture is your voltage regulator. The ozzing stuff is the filling that encases and seals the electronic parts. I'd replace that anyway. They aren't expensive.
One question, does it start right back up every time or does it take a while?
As for your running problem, get a test light or volt meter. It might be easiest to start at the coil and work backwards. If all the necessary voltages are there, including spark to the plugs, move on to your fuel delivery system. Just because the carb is "new", doesn't mean it's right. Stay focused, work on one thing at a time.

http://www.mymopar.com/downloads/1970/70BelvedereGTXSatelliteRoad RunnerA.JPG
http://www.mymopar.com/downloads/1970/70BelvedereGTXSatelliteRoad RunnerB.JPG

 

[PurpleBeeper]

These guys are right......99% sure it's the ballast resistor which is white, about 3" long and mounted on the firewall near the voltage regulator in your picture. '70 Road Runners should have a single ballast resistor & I "think" I see a double ballast resistor in the top/left corner of your picture.

Anyway, the ballast resistor drops the voltage from the ignition from 12-volts to 7-volts (?) before it goes into the ignition coil. That 12-volts comes from the ignition switch through the bulkhead disconnect (3 huge multi-wire plugs near master cylinder) via a BLUE wire going into the ballast resistor. When the car is running, a blue wire on the "out" side of the ballast resistor will be about 7-volts (?). ONLY WHILE CRANKING THE ENGINE, the ballast resistor is bypassed & the full 12-volts goes to the ignition coil on the "out" side of the ballast resistor coming out of the same bulkhead disconnect plug via a BROWN wire.

Basically, while the engine is cranking, the BROWN wire bypasses the ballast resistor and gives the ignition coil 12-volts. The second you let off the key (so it drops back from "start" to "run") after the engine is started, the BLUE wire continues to give the ignition coil 7-volts (?). When the ballast resistor burns out (super common), you get the 12-volts while cranking, but never get the 7-volts while running.....so the engine starts for 1 second & dies, starts for 1-second and dies, etc., etc.

 

[Funship32]

Sounds like a ballast resistor to me. To troubleshoot you can jump it, temporarily, to see if it is indeed the issue. You just don't want to run with it that way for very long.

 

[Daniel Flores Jr]

Thanks everyone for your advice, I'm going to check some of these things out tonight when I get back in town!

Appreciate the responses

 

[Daniel Flores Jr]

UPDATE

So I replaced the voltage regulator and the ballast resistor both. I've been going out and starting it and it has been starting right up and running no problems (hadn't drove it due to bad weather). Today was a nice day so I started it up and cruised around for a bit then it just died, tried to start it and original issue is back (go to start turns over vroom and dies immediately) I'm thinking the only other thing it could be is that ignition switch. My question is can that switch be the cause of this has anyone experienced this issue before?

 

[Dennis H]

Did you have time to clean up the Bulkhead connectors?

 

[Daniel Flores Jr]

Yes sir I just removed each one and clean the connections tested and same issue

 

[Dennis H]

Do the headlights work when this happens? Is it like someone turned off the ignition and threw the keys out the window or like the battery was removed?

 

[mmissile]

Is the ballast resistor getting wet in the weather?

 

[Daniel Flores Jr]

Headlights work, gauge lights are still on. Turn key to start it, it turns over fires up for one second and dies.

 

[Daniel Flores Jr]

No rain and is garage kept

 

[bm02tj]

Add jumper wire to ballast from battery so you remove ignition switch if it runs work your way back till you find trouble

 

[Daniel Flores Jr]

 

[Daniel Flores Jr]

Here a video of what it's doing

 

[Dennis H]

I'm done. I replaced an ignition switch for no reason with no fix when having a similar problem.
Others will help. Let us know when you get to the other side so we can all benefit.

 

[mr. b]

my car did the same thing the ignition switch was bad changed it now its fine

 

[Shorthorse]

Would you take a picture of your ballast resistor? The wiring diagram shows a single resistor and yours appears to be a double resistor. Also, this whole thing would be a lot easier if you had a test light.