Suggestions on coughing/stalling

Jon O.

Jon O.

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Indianapolis indiana
1972 Newport.
Yesterday, I took a trip to the hardware store. Ran very smooth, except on the way back. Over the course of about 6 miles, it started coughing more and more. It almost acted like vapor lock, when I started it this morning, it was still having trouble so I don't believe that is it. It is erratic, coughs at idle and under load. It almost dies and then picks back up.
Just about all of the ignition parts have been replaced recently, so I believe it may be a lack of fuel. The timing is correct. Fuel pump was replaced within the last 1,000 miles. Push rod was of the correct length at the time. I pinched off vacuum hoses, and I don't believe it is a vacuum leak.
Where should I start looking?
 
Jon O. said:
1972 Newport.
Yesterday, I took a trip to the hardware store. Ran very smooth, except on the way back. Over the course of about 6 miles, it started coughing more and more. It almost acted like vapor lock, when I started it this morning, it was still having trouble so I don't believe that is it. It is erratic, coughs at idle and under load. It almost dies and then picks back up.
Just about all of the ignition parts have been replaced recently, so I believe it may be a lack of fuel. The timing is correct. Fuel pump was replaced within the last 1,000 miles. Push rod was of the correct length at the time. I pinched off vacuum hoses, and I don't believe it is a vacuum leak.
Where should I start looking?
Click to expand...

Sounds like you have already addressed most of the usual suspects. I guess if it was me, I would check the fuel tank, pickup and all the rubber hoses from the tank to the fuel pump. The problem also sounds like it could be related to an ignition problem - perhaps with the points or one of the crappy chicom condensers. Of course, you may be running an electronic ignition, and I don't know what to do with that, except replace it - if that turns out to be the problem.
 
ballast resistor.jpg


:D
 
Ripinator said:
Sounds like you have already addressed most of the usual suspects. I guess if it was me, I would check the fuel tank, pickup and all the rubber hoses from the tank to the fuel pump. The problem also sounds like it could be related to an ignition problem - perhaps with the points or one of the crappy chicom condensers. Of course, you may be running an electronic ignition, and I don't know what to do with that, except replace it - if that turns out to be the problem.
Click to expand...
Yes, I forgot to mention it is points ignition. I ran through a lot of condensers until I bought an NOS one. If it were the carburetor/ too much gas, I would think I could smell that. Ill take a look at the fuel lines when I get a chance.
 
Jon O. said:
Yes, I forgot to mention it is points ignition. I ran through a lot of condensers until I bought an NOS one. If it were the carburetor/ too much gas, I would think I could smell that. Ill take a look at the fuel lines when I get a chance.
Click to expand...

Yes. Do that and also - as Mario suggested: Check out the ballast resistor. And remember: Ninety percent of all carburetor problems turn out to be electrical. . .
 
How is your ignition coil? A bad coil can give you the same symptoms as fuel / carb problems. Good luck.
 
Coil or coil lead possibly. My truck did the same thing and was missing under load. I replaced coil wire and it helped but didn't eliminate the issue completely. Wound up replacing all the plug wires.
 
Jon O. said:
Yes, I forgot to mention it is points ignition. I ran through a lot of condensers until I bought an NOS one. If it were the carburetor/ too much gas, I would think I could smell that. Ill take a look at the fuel lines when I get a chance.
Click to expand...
Test the condenser even if it is NOS. They heat up and short out. or it can be
mech.gif
 
mrfury68 said:
How is your ignition coil? A bad coil can give you the same symptoms as fuel / carb problems. Good luck.
Click to expand...
Brand new coil, spark plug wires, and spark plugs. Replaced a while before those were the points, condenser, cap, and rotor. All of the times that I have had electrical problems, it has acted different than this. It acted like this once before, about 10 seconds before I ran out of gas when my fuel gauge stopped working.
I think sediment may have clogged the pickup, or there is a crack somewhere and it is sucking air and fuel.
 
Jon O. said:
Brand new coil, spark plug wires, and spark plugs. Replaced a while before those were the points, condenser, cap, and rotor. All of the times that I have had electrical problems, it has acted different than this. It acted like this once before, about 10 seconds before I ran out of gas when my fuel gauge stopped working.
I think sediment may have clogged the pickup, or there is a crack somewhere and it is sucking air and fuel.
Click to expand...

Just because you replaced all your tune up parts doesn't mean squat if there's another hidden issue in the distributor! How's the mechanical/vacuum advance systems shape, are your springs broken/missing? Is the vacuum can toasted on the inside?
Stop lookin at carb & fuel system, look elsewhere for your problem! Good Luck
Are the weights free to move of advance and retraction while driving?
 
stubs300 said:
Just because you replaced all your tune up parts doesn't mean squat if there's another hidden issue in the distributor! How's the mechanical/vacuum advance systems shape, are your springs broken/missing? Is the vacuum can toasted on the inside?
Stop lookin at carb & fuel system, look elsewhere for your problem! Good Luck
Are the weights free to move of advance and retraction while driving?
Click to expand...
Just because your timing is correct by the book it may not what the engine wants.
Keep in mind with today's gas you may need more timing than stock.
Pull a plug and check the color. If it is black,too rich,too white too lean.
What is your idle speed? How much vacuum at idle?
Should be at 750/800RPM with minimum 18 inches of vacuum.
Do you have access to a timing light with the advance feature??
Like Stubbs mentioned, Get one and check the operation of the vacuum advance and mechanical advance..
Personally,I hate points and recommend going with either Pertronix or Mopar Electronic conversions.
I know Stubbs said stop looking at fuel related but..
What is the condition of the carburetor?
Did you set the idle mixtures??
Adjusted the accelerator pump?

Do you have any video of what it is doing??

As mentioned,throwing parts it it alone will not fix it.
Some time test and tuning,diagnostic will get to the bottom of this.
 
Also check the voltage going into the ballast resistor, you could have a corroded connection in the firewall plug or the ignition switch. Also would not hurt to pull the fuel filter and see if it is full of water from a crappy batch of fuel.

Dave
 
I looked over all the fuel lines, no leaks. I shot air into the line from the fuel pump, it is certainly not clogged. It wasn't until after that when I finally saw the black mark from my exhaust on the cement. It's most probably the condenser again. I went through at least 7 of them last year. Most of them didn't make it out of the driveway. Is there anything that would cause high condenser failure other than them being generally defective?
 
Jon O. said:
I looked over all the fuel lines, no leaks. I shot air into the line from the fuel pump, it is certainly not clogged. It wasn't until after that when I finally saw the black mark from my exhaust on the cement. It's most probably the condenser again. I went through at least 7 of them last year. Most of them didn't make it out of the driveway. Is there anything that would cause high condenser failure other than them being generally defective?
Click to expand...

They are mostly made in China now and they are crap, about one third to half are defective right out of the box. About the only thing that kills condensers other than defective manufacture is too high of voltage going in due to a by passed or improperly wired ballast resistor. If you bought a NOS one that was old, they also deteriorate over time from sitting because they pick up atmospheric moisture and eventually short. If you can find the Blue Streak brand, I think those are still made
here. You might also want to check the float levels on your carb as the moonshine blend gas deteriorates those also. Start the engine and turn it off after about 30 seconds, look down the carb throat and see if there is fuel dripping, a sure sign of a bad float or needle valve.

Dave
 
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