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The flexible line appears to be in poor condition when it should have been one of the first things to replace before putting the car back on the road. Even when they look good on the outside they may have deteriorated and even collapsed internally causing blockage which can start out as intermittent before it blocks off fuel entirely. Incidentally, the same is true with the three flexible brake lines.

As for vapor lock, in all the years I've owned Packards from 1939 through 1956 I have never once had it happen, yet it seems to happen frequently to others. Not sure why that is.

Thanks, Don! That line is omly about two years old and came from one of the major suppliers. I put it on before I would've known better to check the ID on the hose. Sorry, should've offered that. Everything on the fuel side is basically new (or rebuilt). The tank is a stainless tank with vented cap, the lines are new, I have a WIX in-line filter before the pump, and bowl-style filter before the carb. The pump is freshly rebuilt, I used the insulators for the pump, bought and installed the fuel pump heat shield. I've really tried to meticulously manage these critical elements.

I just wondered if it was plausible that that line, even if relatively new, might be collapsing when warm. The ID really surprised me, and I would have guessed that might be an issue.

I tend to agree with Don, that is, I'm not sure why vapor locking seems to be such a common issue. My 53 Cavalier does not have this issue.

Do you have something on the line from the pump to the carb to protect it from the heat?

You mentioned that the car died after about 25 minutes, but then after using the electric fuel pump it started back up. How did it run after you started it back up?

I get this feeling that something is being overlooked. The symptoms sounds similar to those if you didn't have a vented fuel cap.

Maybe get a length of fuel line and a jerry can, and bypass the fuel tank and supply line completely to see if that makes a difference.

If your car running hot? Was it a hot day this last time it died? My sense if that the vapour lock, if that's what's happening, is a symptom of another issue.

There are been several new items added, one of them may be at fault, even though they are new or rebuilt.

If the hose wasn’t made of a material that can handle modern fuels, it’s definitely a possibility that it’s gone bad but easy to remove and check. I have also only ever used stock fuel filters which for mine are the glass bowl type attached to the carburetor although admittedly some have had modern paper elements inside. Although many seem to recommend it, I would never put a filter before the pump..

As for all the vapor lock issues that get reported, I would bet that only a tiny percentage are actually vapor lock! Once we convince ourselves of that diagnosis, we start looking for everything that might cause it rather looking for the actual problem. If, as you say, your fuel system has been rebuilt and the pump has the proper pressure, then be sure it has the insulator sleeves and washers, that the heat shield is mounted over the pump and that the insulator is on the line from the pump to the carburetor. Also be sure that the line is steel or stainless steel, not copper.

The vapor lock issue is intriguing, why does it happen to some cars and not others? Obviously several factors, such as, the fuel itself...ethanol , engine operating temperature/cooling system, ambient temperature and the temp of the fuel in the tank, altitude, road speed, etc.

An electric fuel pump will compensate for the issue, rather than cranking and cranking your engine so the mechanical pump can pull fuel back up from the tank. But why do some cars/owners seem to have continual vapor lock issues, and others don't?

Has anyone run a return line back to the fuel tank to prevent vapor lock?

To Don's point, how many times is vapor lock thought to be an issue but it's not? Is there a better way to diagnose vapor lock? At what temp is modern fuel generally vaporizing? The fuel line/carburetor would need at least that temp, correct? This should be something that is simple to check.

Just noodling while I have a coffee...........

Alright, I got updates...

I ended up taking the advice of one of the earlier posters and eliminated the inlet hose and ran a 5/16 line to a barbed fitting on the pump. As an incidental find, the drain plug on the carb fuel filter was partially open, which I'm sure didnt help anything. Took it out figuring I had it in bag. Sure enough, stopped at a light after about 20 minutes, made my turn, got to accelerating up to 55. It completely broke up on me for about two or three seconds at about 35 mph, then came right back. I pushed it to 65 without issue, reduced to light throttle no issue. No assist from the electric pump needed to recover, but it was a very noticeable and heavy stumble. Until that point, it drove confidently under all conditions.

I took some temperatures. The block was between 180° and 190° for drive (ambient temps in the low 80s). The carburetor bowl and fuel filter bowl both read 143° with an infrared. I'm beginning to wonder if it's the condenser? I feel like the fuel is seeming less and less likely (it is 89 non-ethanol with a little Marvel). To reiterate, the heat shield is there for the pump, as are the other pump insulators.

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Joe, this is starting to sound like how my car was acting this spring when it had a bad coil. It was only a year old, but leaked it's oil. The warmer it got, the worse the car would run. It stalled while idling, which it had never done before and then it did it again 5 minutes later. Of course I was showing my car off to a friend! I could feel the miss as we were driving, and as soon as I put my foot into it a bit it would stumble. It was erratic and got worse as the engine got warmer because the coil wasn't able to cool itself and when they get hot they do crazy stuff!

Because it was erratic in nature I had first thought it was a fuel problem, but I found oil residue on my plug wires under the coil. Ah ha! Did a little research and found the my symptoms were consistent with a bad coil. I replaced the coil and problem completely solved! Currently running a Pertronix Flame Thrower coil.

Your issue may be heat related, but nothing to do with your fuel. It may be the coil getting warm and messing up the ignition.

https://www.facebook.com/groups/342912285774974/permalink/7720593731340089/

I think we can wrap this one up, finally. So last night, I put in a new set of points and condenser. Took it out this morning and although it ran smoother and quieter, the onset of symptoms was even sooner than usual. It's about 90° out today. So I returned to fuel and a couple more changes.

1. I removed the beefy check valve I had recently installed from McMaster that I think ultimately put more resistance in the line than the $7 Amazon check valve I'd had in there originally (one was certainly easier to move air through than the other).

2. I returned to the metering rods and again adjusted them to a richer condition (I had also previously installed a #4 washer to shim the vacuum piston as recommended by another poster).

Took it out, let it get plenty hot at a stop light (usually climbs up to about 205° at a stop light). Gave it about twenty seconds of constant acceleration at medium throttle and it easily climbed to 60-65 mph without disagreement and proceeded to cruise. Good grief. Hoping that's the end of that. Thank you, all!

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