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cbarison 12-03-2010 09:42 AM

Fuel quality
Does anyone know if there is a way to check fuel quality in the tank? Is there some kind of kit or chemistry set for sale?

RichH 12-03-2010 10:46 AM

The easiest is to withdraw a small sample of fuel (200-400 ml.), put it into a clear glass container; then, hold the glass between your eyeball and strong white light. If there is any 'haze' to the fuel its contaminated with particles - probably emulsion of water and oil and fungal particles/fragments. If the fuel is 'dark' it denotes the decomposition products of the fungals (asphaltines?) indicating a high probability that the tank walls have a thick (mat) layer coating of biological deposition and 'active colonies' which are using the carbon in the fuel as their nutrient source. Do webserach: "kerosene fungus" and "cladosporium resinae"

If so, the tank walls and sump should be mechanically scrubbed to 'clean' and/or an enzymatic emulsifier such as Starbrite 'Tank Cleaner' should be used in tanks without clean-out / inspection ports.

cbarison 12-03-2010 10:50 AM

good to know I don't have to spend $ to check it out! So water in the fuel will also show up as hazy? It wouldn't seperate? I should take a sample from the bottom of the fuel tank, correct?

Barquito 12-03-2010 10:58 AM

Here is a link that has a lot of info about gasoline... but, doesn't appear to answer your question.

Automotive Gasoline

Maybe pull a gallon out and see if it works in your snowblower, lawnmower, or outboard. My outboard was very sensitive to how fresh the gas was.

pdqaltair 12-03-2010 11:55 AM

I asume we are talking about gasoline, not fuel. Deisel has a different set of problems (biological growth) and the solutions are differnt too.

The most common problems with gasoline is water, particularly if using e-10. I posted some links:
Sail Delmarva: Ethanol and Gasoline and Diesel - References

Other than holding a sample up (for the bottom is best), there is one other simple test. Take your sample and cool it way down (freezer); you will see if the gasoline contains disolved water that may be causing trouble (this sample should NOT be pulled from the bottom, because yuo don't want the free water). Water tends to fall out of e-10 when the temperature drops, because while it will hold a good amount of water in warm temperatures, it will not in cold temperatures. This is one of the reasons we get a lot of problems in the fall.
Review the chart on page 2.

If there is wate in the gas, suspect a leaking gas cap first.

Other than that, the gas should be clear and free of dirt. Octane should not be an issue for an Atomic 4. Loss of volitiles can also be an issue if the gas is quite old (more than a few months) and this is not simple to test for. Some engines are more sensitive than others.

As always, many "bad gas" problems are actually carb problems. Boat carbs seem to need cleaning every 2-5 years, because of the sporatic use. Get a manual--it's not hard.

Gas additives are a waste of time and money (I am in a related business and have tested most). Replace the gas if it isn't the carb. And don't pump it out with a drill-pump (I saw the aftermath).

RichH 12-03-2010 12:07 PM

Nice/useful posts on gasoline assays ....
Totally totally agree on the issue with 'gasoline caps'

pdqaltair 12-03-2010 04:21 PM


Originally Posted by RichH (Post 673128)
Nice/useful posts on gasoline assays ....
Totally totally agree on the issue with 'gasoline caps'

I could have added that fuel additives are a different matter: biocides, cold-flow agents, and detergents really can work, as long as we understand they are for prevention, not cure-alls.

Also, gasoline additives for extended storage (Stabil and some other brands containing polyisobutlyeneamine functionality) (nitrogen, often smelling vaguely of ammonia, if you are alert) are proven to be effective.

Piratesoul 12-04-2010 03:43 PM

buy your gas at a gas station if your marina doesn't sell a lot
check your gas in the sediment bowel
use sta bil and an ethanol treatment additive
run engine for at least 30mins every week in drive
change fuel filter and clean sediment bowel every time you change the oil

HDChopper 12-13-2010 05:46 AM

If you have an older eng designed for leaded gas it wont hurt to add lead additives IMO ... if older eng it would be best to overhaul the head for unleaded gas using stellite seats ect...

It wouldn't hurt to go to the local airport and get some av gas 101 or 110 oct. what ever thay got and run through it once in a while ....yes I know it's very pricy,

hellosailor 12-13-2010 06:31 PM

cb, don't be shy. Tell us what kind of fuel it is, how many thousand gallons you've got, why you don't know what it is or where it came from...You know, give us the big picture and you'll probably get better answers.

Put a tablespoon of "fuel" in a black plastic lawn leaf bag, opened up all the way. Tie a knot in the big, keeping it fully inflated. Let it sit out in the hot sun for six hours from ten to four.

Now, touch a flame to the bag. If it goes BOOM and then there's this horrible ringing in your ears and scalded feeling on your face, the fuel is still good. For something, at least. (Same test works for gasoline and diesel alike.)

There are other tests, but none quite so simple.

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