Vapor return or liquid return line?

Dana67Dart said

The fuel "vapor" filters have a small bleed hole so vapor can escape but if there is no vapor a small amount of fuel will be escape there.

If you can find a ethanol free gas supplier near you, run your tank down to as close to empty as you feel safe and then fill full with ethanol free, and see if your issue goes away with all the lines and filter as it was before the filter change.

Pure-gas.org

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@RustyRatRod pointed me in the direction of the factory repair manual (insanely better than the Hayes I have by the way...) it appears that second line is the vent that used to run to a charcoal canister which has since been deleted. I'll try your idea about the ethanol free route but I'd still like to figure a way for adding a vapor return line as a fail safe. Would I just look for a sending unit with a return line built in?