Additives in modern fuel eat rubber, so fuel lines tend to soften and weaken and seals tend to degrade. It's advisable to replace all the fuel lines in any older car. Whether this contributes to vapor lock, I dunno. But the volatility of modern fuel is different and that could cause it. Are you sure it's vaporlock and not a collapsing fuel line preventing the pump from being able to suck fuel from the tank to the carb? I live in a hot climate and drive the car in hot weather and have yet to have a vaporlock problem in nearly 15 years, knock on rare genuine walnut... Chris in LA Currell Pattie (currellpattie@xxxxxxxxxxx) wrote: > Is there something about modern gasoline formulations that makes older cars, > like our Imperials with mechanical fuel pumps, more prone to vapor locking?