68 etype with a series 2 engine. The car turns on, idles great for as long as you want, and then as soon as you drive and the engine heats up after driving about 1/2 mile, the engine will shut off. Let the car cool down for 20 minutes and it will start up, only to do it again. We have replaced the fuel pump, coil, rebuilt the distributor, bypassed the ignition switch, made sure there is not a vacuum in the fuel lines, and cleaned out the carbs, chokes, etc. When it dies, there is fuel visible in the small bowl so this does not appear to be a fuel line issue or a vacuum being created. I'm desperate. Has anyone ever seen this before?

 

try using an 1 gallon gas can attached to fuel bowl to take pump tank, etc out of equation and start working the problem piece by piece. vapor lock could still be an issue or an obstructed fuel line, etc, Sounds like starvation except for the fact it is only when heated up. My 55 T-bird would do this but due to hot fuel line so I wrapped in a insulating material and it stopped it.

 

thanks. How do you safely attach a 1 gallon gas can?
also, when car dies, if you open the gas lid to expose the gas tank, there is no pop/whoosh like a vacuum has been created

 

Could be condensor. If it was replaced in the distributor rebuild, do you have the old one to try? Being new doesn't mean it's not faulty. Would also be good to test for spark when the problem is happening.

 

there is no spark, and when the car is driving, there is no jerk in the car like the spark plugs are not firing, but I'll check with mechanic about condensor. Thx so much

 

So, if there is no spark at plugs or coil when the car shuts down, it is an ignition problem, not fuel. If you don't have electronic ignition (eg Pertronix) then problem is most likely condensor or coil. Points and rotor are not likely to be affected by temperature.

 

I have a plastic can with a hose attaches to a nipple threaded in and a rubber fuel line attached that I use to attach to the feed line either in front of or after the filter. Nothing fancy and have used to start an engine especially if fuel line/system is old and gunky to see if engine will turn over. SPark is a good thing and I have seen more than one new coil be faulty and heat will point out this weakness.

 

Just to be clear, this is what my mechanic has done. I misspoke-there is a spark.I'm a body mechanic (surgeon).

Customer arrived stating the car stalls after driving.
We noticed the fuel in the filter bowl was a bright green (watermelon green) customer stated he didn't put anything in the tank other than lead additive which is red.
Tank was drained fresh fuel with a little lead additive was put in, car ran around the shop area with no problems.
on the way home (interstate) it happened again. We pulled the fuel trap to check the tank pickup, all good. Fuel in filter bowl was now clear. We checked fuel pressure and found 1 psi. Installed a new pump, new filter and new fuel. Car drove many laps around the shop area. Customer called stranded after driving a mile at 65mph.
Noticed that if you let the car sit and cool you could start and drive for a 1/2 mile before it started trying to stall, but if you took so long as to have a tow truck bring it back it runs fine.....?
Called a guy (vintage jag in Idaho) that rebuilds pumps, distributors, gauges. He stated the pertronix units get hot and cause a similar symptom. We bought a rebuilt distributor with new points, condenser, cap and button, bought a coil that was suited to points as well. Same thing! Car waits till it's at interstate speeds and tries to stall (like it's running on three of six cylinders) by the time it gets back to the shop it clears up and car idles and revs perfect, take it on a long drive and you'll walk back.
Called the guy again and he said maybe ignition switch. We wired the pump and ignition hot bypassing the switch, same thing. Cleaned all the grounds.
One time it acted up at the shop for a few seconds and choke cleaner in cylinder 4-6 "seemed" to help but it cleared too soon to be sure. Pulled carbs and rebuilt them, took cap off gas tank.... Same thing!
Called a priest who said only the pope could exercise a British car demon

 

Dual stromberg or triple SU carbs ?
I've had the same problem on my car ( dual stromberg carbs) and it turned out to be wrong metering needle's and blocked float chamber vents on air filter side

 

picture

 

Also check if the secundary throttle valve's open up

 

quick question, have the same problem myself, 1970 S2 2+2 dual stromberg, did the last post fix the problem?

 

Thread is several years old so don't know if OP is still around. However, I've rebuilt strombergs and they are the easiest carburetors I've ever rebuilt. It took me something like 4 hours to pull the carbs, take them apart, clean them, and then reassemble with new parts (no web back then and I worked off a shop manual). Your carbs are probably due for a rebuild regardless if one hasn't been done in the last decade or so.