When it dies, have you checked the carb for fuel delivery?
Idles good when initially starts?

 

Idles very well when it initially starts, no problem there.

 

The vent is a good thought. When it dies, open the gas cap. If you hear a 'woosh' then most likely the vent is
plugged and you just equalized the pressure and it should start then.

 

Thanks I'll give that a try this afternoon.

 

Restriction in the fuel filter is another likely reason. What type of filter are you using and where is it located ?

Z

 

Edelbrock inline filter located very close to the carb. I will change that out tomorrow to see if that is the culprit.

 

Yea, no more parts replacing. Recreate the issues and do those two tests suggested: 1. Pull cap to see if vent clogged. If not, 2. Pull air cleaner and see if pumping the throttle gets you fuel squirting. If not, you’ve identified it as a fuel starvation problem. You’ll need to visually check the lines for restrictions, too close to exhaust, etc first, then verify the fuel filter for flow. You got this.

 

Make sure your gas lines are made for "gas". I had an issue once with a friend replacing gas lines that deteriorated from the inside and the fuel pump/system was starving.

 

Does it have points and condenser or......?

 

This was my first thought too. Sounds like a faulty electronic ignition module.

 

Sounds like fuel delivery. Mine had a clogged fuel filter and that's what mine did. Same car as you.
could be module under heat breaking down.

 

... Or a failing condenser, or ...
Time for less guessing and more diagnostics. Back to post #8.

 

OP, you’ve had some great suggestions thus far. I had an issue with my car running fine until the engine would get to operating temp then it would sputter and shut off. Start right back up and then sputter and die again. I worked through a process of elimination.
Search for my old post and hopefully something in there can help. I still run points and the ignition condenser was the culprit to my problem. Good luck!

https://www.vintage-mustang.com/threads/car-started-sputtering-out-of-nowhere.1216114/post-10854030

 

Had similar issue which ended up being fuel boiling at fuel pump (Cleveland)
Ethanol fuel was my issue but my solution was an electric pusher pump rear mounted.
Figured it out using a see through filter. Rerouted fuel line from front to rear of carb as well.

 

I can't tell you if this is your case or not, but with exactly the same symptoms, I was working on my to-do list and did the following (not to fix the problem but just following the to-do list).

I moved the coil away from the engine to the shock tower to eliminate the heat that affects it after the engine gets hot.
I also cut and extended wires (small ones) that go to the coil (Four Films dude Khan with his '67 Coupe had a stall problem; in reality, it was cracked cables that under heat would detach in his case). Then I replaced the fuel line, fuel tank, and put in a performance fuel filter.
I rerouted and moved the fuel line away from the engine to make sure it won't boil.

No more problems.

 

When it dies and wont start, pour a bit of fuel down it's throat and see if it lights up.

 

We can diagnose the problem or just continue to throw parts at it. Most likely you either have a fuel problem, or an ignition problem.

Drive the car until it dies. Open the hood, remove the air cleaner and pump the throttle while looking down the carb. If you have fuel shooting from the accelerator pump discharge nozzles, it's not running out of gas.

If you have gas, pull the coil wire off the distributor and place it near a ground, and turn the car over to check for spark.

One other option is you have a bad ground path between the battery, engine and body. A missing engine to body ground can cause this problem. A 69 will have a passenger cylinder head to firewall ground strap.

 

Circa 1970-71 I had a 69 Galaxie 2drht that drove me crazy with similar situation. It was never consistent as to when it would happen. Some SOB had shoved a couple of small potato chip bags into the gas tank of the prior owner. I got it and out of the blue it thew these no fuel scenarios. But 30 seconds and the bags would float away and it might run fine for 10 miles or 100 miles... And like you when it starts right up again it very frustrating.

 

Now that would be a tough one to diagnose!

 

I have a 71 Mach 1 doing the same thing. To begin with I found that the fuel tank had what looked like a coating on the inside coming off. I replaced the fuel tank, tank sending unit, vent, and hoses. I have replaced fuel filler neck as well just to be sure to have no more of the coating. I cleaned fuel lines, replaced inline filter and even the mechanical pump. It is still dying after it gets hot. Pull fuel line off carb and still no fuel. It has 10 gallons of fuel so I know its not out. Don't really want to put an electric pump.

 

That sounds like the vent is not functioning or yours is creating a vapor lock. Are you using rubber hoses anywhere other than short pieces from tank/sender to line and line to pump?

 

No, I am trying to keep it "original" as possible. There are only three short pieces of rubber hose in the fuel line. The vent has a longer piece but its new as well

 

What vent? Did I miss something? My gas tanks “vent“ through a small divot in the seal of the gas cap. But are we talking about a 71-73 or anther year car…? I’m lost.

 

No, it doesn't. It vents through the vent valve at the center of the cap.

 

Depends on teh year and type of filler neck/cap combo. If your filler does not have a divot, it uses an anti-surge cap with internal one-way check valve to prevent leaks on acceleration. Here's a listing for my '69:

 

Mine is a 71 and has a vent in top of tank going to the charcoal canister which in right rear of engine bay