Mark, I really like your very informative and useful answers to the boaters questions, I often skip or delete many others emails but yours I always read Thanks. Russ. > Date: Sat, 21 Mar 2009 02:41:17 -0700 > Subject: [UnifliteWorld] Re: gas > From: [email protected] > To: [email protected] > > > Within the last fifteen years, changes to environmental regulations > required the introduction of so-called "oxygenated" gasoline > formulations. Oxygenated fuel is intended to ensure that older cars, > which may have tired fuel systems (read: carburetors) would be less > likely to run rich, which results in incomplete combustion and high > hydrocarbon emissions. > > Until a few years ago, methyl tertiary butyl ether (MTBE) was the > principal additive used to oxygenate gasoline. However, MTBE is a > carcinogen, and it has some nasty leaching problems if spilled. > Because of that, use of MTBE has almost completely been phased out, > replaced by ethanol (ethyl alcohol - moonshine). Almost all gasoline > fuel sold today (except aviation gasoline and racing gas) has 10% > ethanol added. > > Most problems arising from the use of ethanol are related to fuel > storage and delivery systems (tanks, pumps, hoses), but as I'll > mention below, some older carburetors have had problems. There are > also some increased storage problems. > > Ethanol's primary effect is that it will soften and eventually > dissolve older rubber compounds. So there have been problems with > older boats' rubber fuel hoses softening and eventually failing. > Modern hoses are specifically designed to resist ethanol degradation, > and replacing the rubber hoses in your fuel system should prevent that > problem. Most fuel hoses made after 1984 and labeled with SAE J1527 > are ethanol safe. Check your hoses, and replace with J1527-spec > hoses. This shouldn't cost too much. Older fuel pump diaphragms can > fail, but modern new or rebuilt pumps will be ethanol-proof. Same for > the rubber parts in older carburetors that haven't been rebuilt in the > last ten years or so. > > For boaters, the biggest problem is with fuel storage, where there are > four separate issues. The first storage issue arises when mixing the > newer ethanol-oxygenated fuel with older MTBE-oxygenated fuel. The > ethanol and MTBE can react with each other, creating a gelatinous > sludge that clogs filters and carburetor jets. This wasn't a problem > with cars, where one mixed tank was usually burned in a week or so. > It's a bigger problem on boats, where a mixed tank can sit for > months. The solution is simple - run the tank almost dry before > filling, and you won't have much MTBE to react with the ethanol. > However, if you haven't had any problem up until now, you shouldn't, > because MTBE was phased out starting in 2005. > > The second storage problem is that ethanol is a detergent, which makes > it a very good cleaner. In older tanks that may have a coating of > varnish from years of holding straight gasoline, the ethanol will > dissolve the varnish, together with any rust, particles or gunk that > was held in the varnish. This will get into your fuel system. The > solution here is two-fold: First, step up your filter change > interval, at least for the first few tanks of ethanol-oxygenated > fuel. That way, you'll get any fuel-tank crud out of your filters. > Second, fuel filters should be capable of filtering down to 10 microns > (the older standard was 25 microns). This will trap any dissolved > varnish particles before they get to the expensive parts like your > carburetors. As I'll mention in a minute, this may also be time to > consider upgrading your filtering system, due to the third problem. > > The third storage problem comes from ethanol's affinity for water. > I'm sure you're familiar with products like Dry-Gas, which were added > to gas tanks to absorb water. Well, Dry-Gas (and similar products) > were -- wait for it -- ethanol. Ethanol molecules looooove to bind > with water molecules, and will hold the water in suspension, and the > water will get burned along with the ethanol and gasoline. All well > and good, except (and isn't there always an "except") that once the > water concentration exceeds about four teaspoons per gallon, the > ethanol and water molecules separate from the gasoline molecules. The > gasoline, being lighter, floats on top of the ethanol-water molecules, > which drop to the bottom of the tank, and due to the water > concentration will make an engine run poorly, or not at all. This is > called "phase separation." Products like Sta-Bil help gasoline resist > phase separation, and should be used on a regular basis. > > However, because boat fuel tanks are open to the atmosphere (through > the tank vents), ethanol-oxygenated fuel has the ability to absorb > water out of the air. This has led to disagreements about long-term > storage. Some experts are suggesting that for long-term storage (over > 90 days), the tanks be kept close to empty. When ready to use the > boat again, fill with fresh fuel which will stir up any phase- > separated fuel and re-bond in suspension. Others recommend that tanks > be topped off before storage, because that will minimize the amount of > air (which carries water vapor that will be attracted by the ethanol) > in the tank. I tend to lean toward the latter belief. Either way, > use a fuel stabilizer. Whatever you do, *do not* block your tank > vent. That can lead to a pressure buildup in your tank, and the risk > of seams or fittings blowing out. > > Because of the higher likelihood of oxygenated fuel to separate, the > use of a very good quality water separator in the fuel system ahead of > the fuel filter is highly recommended. As mentioned, it may be worth > while to consider upgrading the filters on your boat to a high-quality > water separator together with a high-quality 10 micron filter. This > one upgrade, together with replacing your fuel lines with J1527-spec > hoses should prevent almost all fuel problems. Oh, and carry a few > replacement filter cartridges. If your engine begins to sputter or > run rough, change the filters and drain the water separator. > > The last problem, which I don't believe affects Uniflite owners, is > also the most serious: Ethanol dissolves fiberglass resins and > plasticizers. Upper-end boat builders of the '60's and '70's, like > Hatteras, Bertram, and Chris-Craft (the fiberglass Chris's) used > fiberglass tanks. At the time, it was the best tank material > available, and also the most expensive. Now, however, if you have a > gas-powered boat with fiberglass tanks, you're looking at complete > tank replacements. Fiberglass tanks slowly soften and begin leaking > (with the associated potential for explosion from fuel in the bilge). > Black sludge from the dissolving resins and plasticizers is created. > This builds up on intake valves, causing them to stick, and on fuel > injectors and inside tiny carburetor passages, clogging orifices, with > the potential for major engine damage, like bent pushrods. Uniflite > didn't compete in this market, and so used cheaper steel or aluminum > tanks. > > I remember in the mid-70's, when unleaded fuel was introduced. There > were all kinds of scare stories about how eliminating the lead was > going to lead to all sorts of engine problems. It didn't. I think a > lot of the hysteria today (aside from the very real problem of > fiberglass fuel tanks) is overblown. Some simple precautionary > measures (replacing fuel hoses, upgrading filters) should prevent any > problems. Rubber fuel hoses should be replaced on a regular basis > anyway, but I bet very few of us, if we look in the mirror, can > honestly say we've done this. It's been on my to-do list for a > while . . . > >
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