This is at the root of it. The fuel now is not formulated for a system that is low pressure and vented to the atmosphere. The ethanol free stuff is a lot better, but still not nearly as reliable as the fuel available when these cars were new. This fuel is just fine with EFI. A vapor separator at the very least.I have a Walbro GSL395 and a bypass regulator. Modern fuel is garbage at low pressure and prone to vapor lock