72 Dart Struggles and Dies today, Why?

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APK

APK

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I was going to take my 1972 Dodge Dart (318 engine) to a car show this morning. I set the choke and started it. It wasn't a cold morning, 55 degrees outside and the car is parked in the garage all the time. Kicked it off of fast idle and struggled to run, then died. I got restarted but as soon as I take my foot off of the accelerator it struggles to run and dies. It was running good 2 weeks ago when I drove it last, I did not get to drive it last weekend because it was raining all day Saturday and Sunday. Went to O"Reilly Automotive and got some Heet, but tried it again after about 8 hours and no change. Any suggestions?

Thanks for your responses in advance.
 
Choke setting needs re-adjustment, Its either too loose or too tight on the choke door, Or the "vacuum pull off" is not working, You just need a second set of "eyes" under the hood with air cleaner off when 1st. started cold too see how the choke door is acting, then have them either close it more or open it & see if it idles better & doesn't stall while its still cold.
 
Definately fuel air mixture issue. Things to look for a cracked vacuum hose, piece of carbon holding the egr valve partially open, pcv valve/tube/port broken or clogged.
Even a mouse nest in the breather canister could be the cause.
 
the egr valve
Click to expand...

Is that what service manual refers to the "Choke Vacuum Diaphragm"?

Any how I pulled the short rubber hose the runs from it to the carburetor and it was hard, dry and a 1/4 inch crack running from the end that fits on the carburetor. Don't know if the crack was there before I pulled it or resulted from pulling it but I will get a new hose and start there with fingers crossed.
 
egr = exhaust gas recirculation valve. If your 72 has one. Drivers side of intake manifold. Single vacuum line attached. You should be able to get a finger or two in the diaphram from underneath , push up and open the valve by hand. If it doesn't still have the vacuum line attached, forget it. It can't open and get stuck on its on.
72 model factory service manual is a free download here somewhere. I dont have the link.
 
I have a hard copy of the service manual.

I replaced the cracked hose that connected the Choke Vacuum Diaphragm to the carburetor. It did not help.

I did not find a egr valve. There is fitting rising out of the back of the intake manifold, drivers side of the distributor. A small hose runs from the fitting to a black, round, "spotlight" shaped part mounted on the passenger side fender. The hose was cracked also, I replaced it and did not help.

So I replaced all of the other hoses of that same diameter. One that leads from the vacuum diaphragm to thermostat on the air cleaner. One that leads from the air cleaner thermostat to the carburetor. One that leads from the distributor vacuum chamber to a "T", from the "T" to the charcoal canister. I also replaced the connector from the air heater to the air cleaner, it was cracked.

After of that it still did not fix the problem. It runs well with the choke set. Take the choke off and it struggles and dies. Even if you press the gas peddle to keep the engine running, it runs rough with out the choke set.
 
Are you sure the fuel is fresh. May be a fuel pump going south. Could be as simple as a clogged fuel filter. Thats where I would start.
 
Tank was topped off 3 weeks ago, driven 2 weeks ago with no problems, tank at 3/4 right now. Only use 91 Octane.
 
Just an update. Took the Dart to a mechanic, he said the carburetor needed to be rebuilt and they did not do that. Was referred to another mechanic, a "Mopar Guy". He said he blew out the carburetor, had some dirt in it. It's up and running again.
 
APK said:
Just an update. Took the Dart to a mechanic, he said the carburetor needed to be rebuilt and they did not do that. Was referred to another mechanic, a "Mopar Guy". He said he blew out the carburetor, had some dirt in it. It's up and running again.
Click to expand...

Now would be the time to put that new fuel filter on!:coffee2:
 
Now would be the time to put that new fuel filter on!
Click to expand...

While the mechanic had it I had him replace, Spark Plugs, PCV Valve, Fuel Filter, Rubber Fuel Line and some vacuum hoses. The vacuum hoses and fuel line were old and also had paint on them from when the engine bay was painted. The mechanic also cut the old fuel filter in half and said there was no debri in it. It runs smoother now.
 
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