Hey again guys

A few days ago my truck would not run in the cold. I could crank and crank but without giving it fuel, it would not start. If I gave it fuel, it would start but run like garbage.
We attributed this to the choke. I extended my thermostatic choke linkage so that the choke closed further when cold. Excellent, all is well there.
The truck still won't start and it's only -6 celsius here. Not cold.

Previous to swapping to a supersix setup the truck would start in the cold every time. It was pretty much turn key. Not anymore.

The carb base gasket was wet, I noticed so I tightened the mounting nuts thinking that maybe it had a big vacuum/fuel leak going on there preventing it from starting. No change.

What would be causing this sudden cold start issue?

I cant get it to run for any amount of time with the choke flap closed. It will try to start but then just won't go. If I disconnect the choke and leave the flap open, I can get it to start by giving it fuel but if I come off the fuel it sputters and subsequently dies.

In warmer temps just last week it was running fine. Crank for a second, maybe two, then fire right up and be ready to go as soon as it starts.

Any ideas guys?

Maybe the cold is a red herring. Maybe it just stopped running coincidentally with the recent cold spell.

Any possibility you've taken this truck over rough terrain just before this issue started? My valiant had an issue with very poor idle (no idle, actually!)... It ran incredibly rough, only way to get it to keep running was to keep treading the gas pedal.

Turned out a bunch of junk had coated the bottom of the fuel bowl. Jostling over rough roads had stirred up junk in the tank, which was so fine it went right past the filter. A good carb cleaning (disassembled) put it back on track.

- Mac

I was thinking that as well.

Nothing particularly out of the ordinary happened before it stopped running. It ran perfectly fine only 10 hours before it wouldn't start.

I forgot to mention that it did run fairly smoothly at a high idle the first time it started after I fixes the choke. I then gave it a shot of fuel to kick down the idle and it died, wasn't warm enough yet.
It then didn't start after this and I did crank for quite a while...maybe I flooded the engine and blew all chances of starting it after that?

could also be an intake leak. check for leaks... It could be sucking air, and when you close the choke flap, it lessens the amount of air going into the engine.

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What's my best way to check for an intake leak when I can't get the engine to idle?
I wouldn't be super shocked if there was a leak in my manifold but I can't think how I'd check that without the engine running.

Loosen all the intake and manifold bolts and retighten them following the correct procedure. Then try again.

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Casually looking for a Clifford hyperpak intake for cheap.

Fuel side of equation…

Perfect world with choke operating as designed:

During a cold start(first start of day) choke has to be fully closed, but as soon as there is vacuum choke will crack open 1/8 to ¼ inch (depending on carb) for engine to continue running. If after a cold start one were to open choke flap by hand before engine has run for 60 seconds or so engine will stall from lean mixture.
This is normal, by pumping accelerator, accelerator pump is dumping enough raw fuel onto manifold creating an inconsistent rich condition for engine to stumble along, and as explaned above once pumping stops engine leans out, and stalls.
This could be from incorrectly torqued bolts, but more likely all that pumping wet down throttle butterfly, and fuel oozed out along shaft wetting base of carb.

Aside from internal carburetor problems such as dirt, sunk float, I suspect that you flooded the engine. Flooding during warm weather often can be overcome by holding throttle wide open, and turning over engine for a bit to dry plugs enough to once again fire. In cold weather plugs don’t dry very fast, and require removing them from engine to be dried. It doesn’t take much to flood a real cold carbureted engine practically if the carburetor is out of adjustment, is a high mileage unit, or has sucked up some crap from the fuel tank.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

^ good info, thank you.
I'm leaning towards the flooding idea as well.
Oil smells of gas this morning which only confirms this idea. I'll be changing the oil this afternoon and trying again.

Changed the oil and tried starting it up again. Did the same thing it did yesterday. Ran at a high idle fine for a minute, tops, then started to sputter and died. Wouldn't start again afterwards.
So I decided to pursue the vacuum leak idea. I loosed all studs and worked from the inside out, tightening them again. All are now tight and I'm fairly confident there isn't a leak there.

I can still get it to run if I give it fuel but it runs terribly and will die if I come off the fuel.

I pulled the plugs and this is what I'm dealing with on each and every plug:





Completely black, all of them. This is one of the better looking ones.

Black comes from a rich mixture right? Could these fouled plugs be my problem?

Tried running it without the choke at all and it seemed to run pretty well, although I did have to give it a lot of fuel...it proceeded to sputter and die if I let off.

Blag plugs = running rich.

You say it runs good at high idle but die as soon as it comes off high idle. Try letting it run at high idle until the choke opens fully on its own, then drop it down to curb idle. Does it die?

If it dies, check these things:

(0.5) Verify choke is set up correctly and to the proper measurements
(1) float level
(2) curb idle speed screw turned in far enough to contact the stop and hold the throttle open slightly
(3) base timing correct
(4) PCV valve installed and functioning
(5) If equipped with power brakes, make sure no leaks on the brake booster hose and it is sealed tight to the manifold
(6) Disassemble the carb and check for correct gasket usage and any internal damage and leaks. Especially check for throttle shaft wear if you are using a BBD.

_________________
Casually looking for a Clifford hyperpak intake for cheap.

I checked the carb before installing it only 2 weeks ago, seemed fine to me. Not totally sure about the float level though.
I'm consistently getting a backfire out of the carb now too. Timing?

It will die off the high idle on its own. It'll run for maybe 30 seconds or so on high idle the first time I start it during the day. 30 seconds later it dies and wont start again.

I still want to lean towards a vacuum leak. Like Reed said, check your break booster, wiggle the hose around, do a visual as you move it around.
check out this video, this guy checks for leaks using a cigar while the engine is off.
Maybe it will help.
http://www.youtube.com/watch?v=zMok2y05jNE

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Slant power!!!
At least I try...

Stalling and backfire through carb are typically signs of a lean condition.

_________________
Casually looking for a Clifford hyperpak intake for cheap.

could the lean conditions be caused by extra air entering engine through a vacuum leak?

_________________
Slant power!!!
At least I try...