CS-19 I've had this same Problem with my engines also.
I've had my Hot rod 57 sitting for two years. When I went to move it before winter, it started to act alittle funny like it was out of gas "It has Holley Electronic fuel injection" I checked the tank and noticed on the return line it was spitting black globs or chunks in the tank.:idea: :idea: I then went and changed the fuel filter. Thats when it got interesting!!!!! Pulled the Aeroquipt hose off and the inside of the hose looked like it was made out of Black Permatex goop. The Pump Gas Fuel "ethanol CRAP" Had sofftened the lines to the point they were Moosh.
So yes I beleive the Ethanol in the fuel had turned the lines bad from sitting for that time.
Damn Exotic fuels