70 ROADRUNNER WILL START BUT NOT STAY RUNNING

[soundhd]

Have 70 Roadrunner (383/auto). Have owned it for going on 8 years now. Has always started with out any problems. Have always used ethanol free aviation gas since I have owned it. Started this past winter (live in Michigan). I do have it for sale and was expecting someone to come over and take a look at it so a day before I went to start it and pumped the gas pedal a couple times like I always have done in the past, it fires right up once but dies. The only way I could get it to stay running is to sort of keep the starter going for a few seconds until the engine will run on it's own then it is running very rough but after a minute or two it starts smoothing out and once warmed up runs fine (the expected buyer never showed up or called). Anyway tried it again a few days later and the same thing happened. It has an electric choke and it seems to be working correctly so at this point I am thinking it is the cold (normally I never start it during the winter months). Tried it again a few days ago (much warmer 60 degrees)...same thing happened, got it going, smoothed out and took it for a drive (drove fine), brought it home, parked it in front of the house garage to put fuel in it....was at 1/4 tank, added 5 gallons (took about 10 minutes) so the engine is still hot, went to start it and the same thing happened but the only thing that was different I got it running a lot faster, then parked it in the barn where I keep it (so it is not a problem with cold motor).
The choke was taken apart and checked and cleaned...is working correctly. Replaced the resisitor (ceramic piece on the firewall) along with the voltage regulator and ignition module. Have a AFB Carter Competition Carb model 9636-5A 240-1; Have ordered a re-build kit for it. Today I tried putting some gas directly in the carb and still had the same problem...started and died...Correct me if I am wrong but if it would start and not stay running at least for a few seconds by putting fuel into the carb I am thinking this is maybe not a fuel problem but maybe an electrical issue?
Any suggestions and where to start looking for and the steps to do it to fix this problem would be greatly appreciated.

Thanks
Puzzled in Michigan

 

[Big Bad Dad]

I know what you said, but still, I would check the fuel filter for trash or partial blockage.

 

[1967coronet]

It knows your trying to sell it.
Cars have a soul. Yours is not happy right now.

 

[Ranger16]

Once it lights, can you keep it running by feathering the throttle?

I don't know anything about that carb, but it almost sounds like the choke may still be closed too much after it starts.

 

[Don Frelier]

You should be able to take the top off the carb without needing a rebuild kit.
I would definitely take the carb apart to clean and inspect.
And yes it should run 3-5 seconds by dumping an ounce of gas down the carb.
Air filter? Cap, rotor, wires? Age and conditiont of these?

 

[1967coronet]

Like posted make sure your getting enough fuel and that the choke is open.
Check the cap and rotor for crud, pull a couple plugs and see if its gas fouling. carter is near the same carb as a edelbrock , may have accelerator pump issue. May need one.
Back out the air/fuel mix screws and give each a little shot of air or carb clean then re install turn down to bottom then back out 1 and 1/2 to 2 turns.

 

[Don Frelier]

Temp fix: connect a wire from the battery to the pos side coil. You will be able to keep it running but the key won’t shut it off only disconnecting the wire will shut it off

He has an electronic ignition.

 

[myk r sanchez]

It knows your trying to sell it.
Cars have a soul. Yours is not happy right now.

Its foretelling of the regret the seller will feel years later for selling the car...

 

[mikeyfrano]

He has an electronic ignition.

Sorry I didn't read your whole post so it won't work for your problem anyway

 

[Don Frelier]

Another simple easy thing to check:
Pull the wires (one at a time) out of the cap and check for corrosion.
Same thing at each plug. The wires may be fine but they can get corrosion from dissimilair metal.
* And bulkhead connector on the firewall.

 

[soundhd]

All plug wires and coil wire are new as of late last summer. Choke is operating correctly. As for the fuel filter why would it be hard to start but will run fine after it warms up? Wouldn't the fuel filter be "clogged" all the time and keep it from running once it does start? Dist & rotor looked OK.

 

[BLK 68 R/T]

To much fuel perhaps? Could be a float or needle and seat allowing to much fuel. That could explain the running bad when cold and also after hot if it partially floods itself.

 

[HALIFAXHOPS]

Check the pick up in he distrib. They do funny things when they are going out.

 

[Bruce Gregory]

So I had something similar on a Chev (I know, I know) ZZ4 motor - it progressively got harder to start and wouldn't run but I could persevere and eventually it would. Then I noticed oil leaking from my fuel pump - the diaphragm had started to disintegrate. If your fuel filter is after your fuel pump, it's an easy check - take it out, bang the inlet on the bench and see if crap comes out. I'm sure in my case it was ethanol related, but the symptoms are sure similar.

 

[Ernie ingling]

Ballast resistor

 

[Don Frelier]

Ballast resistor

The ballast is either good or bad.
If it's a dual (4-prong) it could fire during cranking and not run position or vice-versa.
But if the run segment is bad he wouldn't be able to run and drive it.

He might want to try this to check spark in run position:
1. Find a good loose spark plug (or remove one)
2. Connect one of the longer wires and ground the plug a jumper cable would work.
3. Key in Run position
4. Jump starter relay and crank the engine(Make sure it's in PARK)

Spark should be blue/white and crisp not yellow or lazy.

 

[bandit]

Mice are a pain in the butt over winter. You said the issue just popped up.... Maybe one got into yours somewhere while storing. Nest, chewed wires... They will crawl up the tail pipe too and nest

 

[eldubb440]

90% of carb problems are electrical