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 . . . --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "UnifliteWorld" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/UnifliteWorld?hl=en -~----------~----~----~----~------~----~------~--~---
