Engine dies, not fuel issue?

Doug in New Freedom wrote: Might be Vapor Lock in the Gas line when the engine heat combined with possibly the 100 degree temperatures we've had this summer is boiling the gas. Ethanol (alcohol) gas seems to contribute to this problem as it boils faster the non Ethanol. Check you gas lines to see if the run on the exhaust manifold or other High Heat generating areas. It goes away when thing cool down.

I absolutely, positively agree on this. the Carter BBD and the older 1bbl Carter YF really don't like ethanol fuels, and percolation is a real issue with these. Using the 'Pure Gas' app on your phone can help you locate non-ethanol fuels if you don't know where to look. I just drove my Concord across Kansas in 103-104 degree temps with no percolation issues at all - and was running the AC the whole time.

Also - is the return line from the dual-outlet stock fuel filter still in place and functioning?  If you aren't getting a good return flow to the tank - or if you have disconnected the return line and are using a single outlet fuel filter, the electric fuel pump can actually make matters worse by not having anywhere to send excess fuel.

i'm sorry to disagree, but the YF nor any other carb is gonna "know" if there's ethanol in the gas. gasoline is not ever a single substance anyway, its very complex. the differences between even best and worst will be microscopic. all gas engine fuels are complex blends of fuel that varies with location and geography. https://en.wikipedia.org/wiki/Gasoline

far more likely are fuel delivery, or temperature issues.

maybe some "tests" to narrow things down?

* does it only do it warmed up? if you drive off "cold", does it die after 10 minutes?

* is it "warmed up" or "10 minutes" that's the correlation?

* what if you get it warmed up in the driveway? does it die when you first pull out?

* does it die on uphill, or downhill? (front-mounted electric pumps more likely to fail on uphill).

* loosen/remove the gas cap, see if the problem "goes away". maybe there's a return line/vent issue.

* drive with the air cleaner off: let it die on the road. turn off the ignition, coast to a stop. look down the throat and manually flip the throttle: do you get normal squirts of gas from the accell pump? or is the carb dry, no gas?

* get the engine all warmed up, *then* do the fuel pump volume test (in the TSM, but basically, pull the hose of the carb, into a container, and actually measure gas delivery volume).

* if you have an electric pump, 99.999% of them must be installed back with the tank, ideally gravity fed to prime them. electric pumps are nearly always vane pumps: they PUSH, they don't PULL. the old mechanical diaphragm types, mounted on the engine, are designed to pull, with that giant diaphragm. electric pumps sometimes sort-of work up front, pulling, but when things go non-ideal, they stop pumping. eg. bubbles, a small entrapment of air/fumes, the impeller spins, fuel delivery stops.

* vapor lock requires a lot of underhood heat. does portland get that hot? like persistent over 95?

testing always beats theorizing.

i'm sorry to disagree, but the YF nor any other carb is gonna "know" if there's ethanol in the gas. gasoline is not ever a single substance anyway, its very complex. the differences between even best and worst will be microscopic. all gas engine fuels are complex blends of fuel that varies with location and geography. https://en.wikipedia.org/wiki/Gasoline

Tom - not to hijack the thread, and to be sure, I absolutely respect your research and use of science with all you have done on your Rambler - I read your posts and your website regularly and am always thoroughly impressed.

However - my personal experience over several years now with the differences in how these carbs operate on ethanol blends and pure gasoline is pretty self-evident. High underhood temps+ 10-15% ethanol fuels = percolation and non-hot start and lean-surging while running. High underhood temps + pure gasoline = easy restart and no in-operation lean-surging. I do it over and over and over, and I get the exact same result. Why run a carb that was never intended to have alcohol blended fuel in it when there is an alternative that simply makes the issue go away?  Yes I live at high altitude, and yes, I know that exacerbates the issue.