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I was poking about and found this article from Down Under. It addresses a lot of questions we are all having about the Black Goo.
Here is the exerpt that applies:

7.2 Deposit Formation

Various studies investigating deposit formation on engines using ethanol-blended fuels have been performed on four-stoke and two-stroke engines. The majority of work on four-stroke engines is of automotive background.
Four-stroke engines may experience intake system deposits (ISD). ISDs are the deposits discussed in any significant detail by the various authors of the literature reviewed. In particular, deposits on the back of the intake valve is referenced as the area of most concern. This concern is clear due to the intake valve and seat area presenting the flow restriction point in the intake tract of modern engines.
Intake system deposits are reported by (13,14) to be more prevalent with fuels containing alcohol. The authors14 explain that gasoline contains two types of additive packages to control deposits. The two different additive packages are formulated to control deposits on the pintle of the fuel injector to ensure accurate fuel metering and to control the deposits on the surfaces of the intake system, particularly the intake valve, to ensure the engines charge airflow is not compromised.

Their detailed testing has shown that adding 10% by volume neat ethanol to gasoline with adequate ISD additive increased intake valve deposits by more than 350%. [ed: this BOLD was added by PETER]

This is not only due to the dilution effect but also due to an antagonistic effect since neat ethanol blended at 10% by volume with gasoline without ISD additive increased intake valve deposits by 37% over the gasoline base without ISD additive. Increasing the ISD additive by 50% over the normal concentration in gasoline was found necessary with 10% ethanol blends in order to achieve the same deposit control as with normal ISD additive levels in gasoline. Some of the experiences reported by (14) are confirmed by (11). Firstly that intake system deposits have been found in the intake valve area, and also includes the intake manifold area; and secondly that the deposits can be controlled with higher additive levels than would be required for gasoline only11.
Crankcase scavenged two-stroke engines may experience detrimental deposits in the piston ring land area as documented by Kasperson and Reynolds28. The piston ring land deposits tended to cause ring stick, where the piston ring becomes stuck in the pistons ring groove. These ring land deposits are common in engines operating on gasoline; solvents and detergents in the fuel and oil control the severity of the deposits.

11 K. Owen and T. Coley, 1990, 'Automotive fuels handbook'
13 J.C. Guibet, 1999, 'Fuels and Engines'
14 Clifford M. Shiblom and Gary A. Schoonveld, 'Effect of Intake Valve Deposits of Ethanol and Additives Common to the Available Ethanol Supply' SAE 902109

Note: "ISD" stands for "Intake System Deposits


If you have more interest here is a link to the whole article:
http://eriss.erin.gov.au/atmosphere/fue ... ility.html



And here is a link to another interesting article that discusses further the problems with ethanol, detergent gas, ISD's and intake valve deposits (IVD's)
The whole article is very informative, but specifically check out chapter 4 page 20
http://64.233.161.104/search?q=cache:aR ... =clnk&cd=4
That last one is in HTML format because it is faster on my old computer that way, but at the top of the article there is a link that will take you to a PDF version if you prefer.

Note how they discuss that the type of engine, the specific arrangement of specific valves, and the way you "drive" all can effect the formation of deposits. Particualrly the post shut down heat soak.

All of this suggests to me that the fiberglass tank may not be the source of the black goo. We also do know that some fiberglass tanks going back as early as the late 1960's are perfectly OK with ethanol. Some underground storage tanks used at gas stations have been tested and certified for continued use with E-10 going back that far. Keep in mind, though, that this doesn't mean that all fiberglass tanks are 100% OK. There still might be issues with some fiberglass resins and ethanol. The question is which ones and how do you know what you have in your boat?


Lastly here is a link that discusses problems with phase separation in a fairly intelligent manner:

http://64.233.161.104/search?q=cache:1o ... lr=lang_en
Note that tis points out that up to 80% of the ethanol can come out of the gas with water and phase separation.

P.S. I am now a fan of the new style bbs. It was a piece of cake to put up these links!

I forgot to add that the outshoot of all this is that simply changing to metal tanks will not solve the problem of intake system deposits!

Peter

Are there ISA's that WILL help with the problem??

I know that there is a helluva lot of stuff in my original post, but you should go through the articles in their entirety in order to gain the best understanding of this problem.
My read on it is YES there are addititves that clean out the deposits. Chevron Techron is the one that seems to be most commonly mentioned, but there are others.
The thing is though, that such addititves probably should be used on a once in a while basis if the fuel is coming from the supplier with the correct amount of "detergent" in it for ethanol use. If the fuel is suspect then treating the tankful with some additional addittive seems wise. How much? I haven't found that out yet...it just tells us 50% more than they used prior to the introduction of ethanol.
The good news is that now this information is out there we should expect the fuel suppliers to blend in their additives accordingly. The bad news is if you mix old fuel and new fuel you will upset the balance toward making more deposits.
Also there is good news about TAME and ETBE in the articles as well. Ethanol is not the only choice for oxygenating gasoline, and after this fall it will be up to the oil companies which additive to use, ethanol no longer being mandated. TAME and ETBE are cheaper and easier for the fuel companies to use, but ethanol is subsidized by tax incentives, so it will be an interesting economic balancing act to watch.

Peter, this is some good info and may explain some of the randomness of tanks being affected.

I'm still in the wait and see category. I'll fill with ethanol in a week or so and will have extra filters on hand and be adding chevron techron to the first tank.

I'll also be adding an aux tank of 110-150 gal (had one before, just hadn't replaced it). Once installed I can isolate the fg tank if needed. I'm in the chesapeake so the limited range won't be that big of a factor, just an inconvience.

Thanks again for the info.
br,
JohnD

Make sure you remove and/or burn off all the old gas before going to E-10. Then try not to switch back and forth.

Try not to leave a whole tank of gas sitting around for weeks at a time because of the water problem. Just load what you are going to use in the next several days and try to run the tanks down.

I know that E-10 isn't as pervasive in the Chesapeak as it is elsewhere. so the switching back and forth between E-10 and normal old style gas could be an issue.

Good luck,and keep us all posted if you find out more.

Peter

Yup, that's what I plan on doing. I'm on my last tank of non-e-gas and will burn that this weekend.

Then add techron and fill 30-50 gal for the next week for local runs and to get short hauled before Atlantic City trip. Change of filters on hand to replace when necessary. That way hopefully I'll have all the bugs out before I make the long run.

I'm in the mid/upper bay and the non ethanol stuff is well over an hour away. Besides, I'll have to face it sooner or later anyway.

I'll keep everyone posted.

-jd

Keep us posted on how it works out John.

If I remember correctly, Techron is such a good cleaner, especially in fuel injected engines, that an oil change is recommended after its use so as to remove oil which may have had its lubricating capability compromised by the Techron. Please correct me if my memory is at fault, but if not, it would seem that the routine use of Techron as an additive may create its own set of problems.

You are correct. There is a concern that Techron used in large amounts as a deposit cleaner can cause engine oil to loose its lubricity. It has not been a concern that Techron in normal amounts used as a deposit preventer causes the same problem.
That is why it is probably best to use it in large amounts only occasionally in order to clean out deposits which may have formed, and then to change the oil afterward.

What I don't know is:
A) how much Techron is in the gasoline you buy at a Chevron station.
B) if Chevron has changed their formulation to reflect the need to increase the amount of Techron by 50% in E-10 fuels to prevent the huge increase in the deposit formation
C) how other suppliers (Exxon-Mobil, Shell, etc.) are dealing with the same thing
D) if there are any adverse effects of adding Techron to fuels other than Chevron's. i.e. mixing different brands of cleaners.
E) if Chevron has upped the Techron content in its fuel, how does this effect oil life.
F) What other products are available that accomplish the same things, and which ones are most effective.

I'm thinking I'll probably run some Techron through in a clean out mode once a month or so, followed by an oil change. The actual timing of how often will depend on how much use the boat is getting.

Peter,
outstanding read, nice find!

Here is a link to Chevron Techron information.

http://www.chevron.com/products/prodser ... plus.shtml

Note that they mention that up to 50% of fuels have too little "detergent" additive.....just the minimum required by law.

Peter