I have read where the ethanol in gas was causing some older rubber lines to deteriorate. I have added stabil to one injected car that sits a lot.

here is one small article:

Ethanol Fuel - What's the dangers?
Simply put, ethanol is an excellent SOLVENT (dissolves plastic, rubber, fiberglass and more), and unlike MTBE ethanol will ABSORB WATER, which can cause serious problems to some engines.