My daily driver is a '70 C20, 350, auto. This is what I have learned:
Ethanol blend fuel boils at a lower temp than EF. Up to 10% blend was bad enough, now that we are at 15% in most blends, it is worse. Higher percentage = Lower boiling point. A mechanical pump puts out ~7psi which is not enough to compress the bubbles,. This results in cavitation leading to misfires and possibly vapor-lock on hot days.
Ethanol eventually breaks down to sugar (like that nasty High Fructose Corn Syrup we are told to avoid) and water. If your rig sits long enough, the water will rust out what it can; the sugar will plug what it can and you are left with a rig that wont run. Inline filters eventually gum up and you can get stalled on a cooler day.
So, Spend more for EF (now over $1 more/gallon in my area)
or install an electric fuel pump which puts out about 40psi. This will compress the bubbles. However, if you don't drive a lot, you still have the break-down issue from old fuel. (Some of us can remember the days when a rig could sit for years and you could head out with a fresh battery; the handle from under the seat, or a push down the hill, and crank it right up!)
Best
RE
