10% ethanol issues

After two years of working on my 78 Penn Yan with twin 318s, I thought I had it finally figured out until I put 10% ethanol fuel in the tanks. I now have idle problems on both engines and the older engine won't hold rpms above 3000. The marina workers said they had to buy all new gas lines for their small rental boats because they wouldn't start. Luckily I can get to the tanks and may have them replaced. I will have to clean the carbs and replace all the filters again. I hear you should also go to 10 micron water separator filters.

As I read throught the posts I see many are having similar issues with rpms and idling. Anyone else believe this is due to ethanol?

Thanks,
Jeff

In my case it isn't, since ethanol hasn't found it's way to either of the fuel docks I use (yet). But making the switch to ethanol can lead to a number of problems, which are well documented.

Don't yank the tanks out yet.

What you're experiencing is classic "evil-nol" sabotage: The crud in your tanks--that was perfectly happy to sit there for years--has been stirred up by the ethanol, which is a 'different' solvent. The result is slugs of crud that are plugging your filters. I had to change mine several times the first year we had to use that crap, but the problem went away and has not returned.

I suggest the following: Equip your boat with a coarse water separator/ strainer (NOT a filter) of 25 to 30 micron (and no finer). Next, AFTER the fuel pump install a 10 micron filter. And change them both regularly.

One more point: If your carbs have a tiny filter installed inside them (many do), toss it out and put a large, metal, in-line filter before the carb.

The above setup has been well proven out there in "Evil-nol" land.

Jeff