Mystery Foreign Matter in Diesel Fuel Tank

Gene B

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Prior owner had some issue with crystal-like debris clogging fuel line pick-up in the port side fiberglass fuel tank.
Debris never made it to the racor but would restrict fuel flow/cause rpm drop.
Best description of the matter was that it looked like diesel colored rock candy., that could be crushed between two fingers.
Two hand holes were cut in the tank, on either side of the tank baffle, and approximately a cup full of the matter was loosely scraped out of the tank bottom.
Tank is in good shape, no sign of deterioration at all. Pretty sure something went into the tank that layered and solidified on the tank bottom.
Picture of the debris is attached,; it's dried out now and easily breaking down into a powder.

Once the tank was cleaned, the engine runs fine, no drop of rpm either fuel tank.
The starboard tank has not been inspected.

Would be interested if anyone would venture a guess as to what the debris is.

Thanks

Gene
thumbnail_IMG_5598.jpg
 

Downrigga

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Prior owner had some issue with crystal-like debris clogging fuel line pick-up in the port side fiberglass fuel tank.
Debris never made it to the racor but would restrict fuel flow/cause rpm drop.
Best description of the matter was that it looked like diesel colored rock candy., that could be crushed between two fingers.
Two hand holes were cut in the tank, on either side of the tank baffle, and approximately a cup full of the matter was loosely scraped out of the tank bottom.
Tank is in good shape, no sign of deterioration at all. Pretty sure something went into the tank that layered and solidified on the tank bottom.
Picture of the debris is attached,; it's dried out now and easily breaking down into a powder.

Once the tank was cleaned, the engine runs fine, no drop of rpm either fuel tank.
The starboard tank has not been inspected.

Would be interested if anyone would venture a guess as to what the debris is.

Thanks

Gene
View attachment 133324
Its dead bacteria
 

Gene B

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I have a sample out to a lab for analysis- will share the results.
Cant find anything in the internet searches for fuel/tank bio issues that resembles this stuff.
 

Brooksie

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dead bacteria I've seen was black, but it wasn't well dried like that. Taste? Could someone have put sugar in the tank?
 

Downrigga

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It will be interesting to figure it out. Did you happen to wet any of it? Just wondering if it will smear in between your fingers when wet or is it more crystal like when wet. Black is usually the result of polymer chains forming when the fuel becomes unstable and begins the process of trying to return to a solid state.
 

Brooksie

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Yes, the black stuff was more like dried asphalt. Many years ago I had a "Blue Flame" super high efficiency furnace. Drove my burner service guy crazy b/c it would heat my house with, as I recall, a .5GPH nozzle or smaller which he had to order specially. At cleaning it left behind in the chamber & pipes a white/tan powder, never any black soot anywhere.
 

Downrigga

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Yes, the black stuff was more like dried asphalt. Many years ago I had a "Blue Flame" super high efficiency furnace. Drove my burner service guy crazy b/c it would heat my house with, as I recall, a .5GPH nozzle or smaller which he had to order specially. At cleaning it left behind in the chamber & pipes a white/tan powder, never any black soot anywhere.
Your bringing back memories now. Those blue flame funnaces were a bitch to tune up properly. They were kind of dangerous if not properly tuned up. We did everything possible to get rid of them. Its funny you should mention that because the first thing i thought of when i saw the picture was its coke or dryed sulphur but todays diesel is pretty much sulphur free. It would also have to go thru the burn process. There are several types of bacteria and some are green some are brown and some are tanish. Not sure what else it could be. Hopefully he will let us know. They can all become black if the fuel has broken down. If it turns to a slippery slime when wet its most likey going to be a bacteria.
 

Brooksie

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So was the stuff in my "Blue Flame" furnace sulfur? It was very, very efficient if you had free service from your oil dealer. I eventually turned that house into a rental and shortly the heat exchanger burned out and I replaced the furnace. Why couldn't that be done properly with Inconel exchanger and proper filters to protect the very small nozzle? Especially with low sulfur fuels to eliminate the big cleaning. What an oil saver that would be... I'd buy one in a minute.
 

Downrigga

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So was the stuff in my "Blue Flame" furnace sulfur? It was very, very efficient if you had free service from your oil dealer. I eventually turned that house into a rental and shortly the heat exchanger burned out and I replaced the furnace. Why couldn't that be done properly with Inconel exchanger and proper filters to protect the very small nozzle? Especially with low sulfur fuels to eliminate the big cleaning. What an oil saver that would be... I'd buy one in a minute.
Yes it was sulphur. Any nozzle that small should really be fueled with kero. They do make inline filters now that get installed in the jet line that would have made a big difference back then. Dropping the sulphur was one of the best ideas ever. We open up systems and find the very clean with no soot to remove. Its nice. Blue flame was a great comcept but it had way to many callbacks for fine tuning if you were not pretty good with them. Our industry is not that savy.
 

Gene B

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when it came out of the tank it, size and shape it looked like rock candy crystals but with some pressure it could be crushed between two fingers.
pebble sized loose pieces were clogging the fuel pick-up tube, none made it to the racors. What wasnt loose, was scraped from the bottom of the FG tank.
 

Gene B

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Results came back indicating the following, quoted from the report

“This is a baseline read-out on the submitted
sample. Debris analysis: There are three primary
debris components present, a clear glass bar
particle type, a black/dark carbon particle type, and
a white crystalline particle type. The clear glass
bars are most likely filter fiber material from a
synthetic fiberglass media filter that was damaged
or had some type of media release. This being from ppm a fuel system, the black debris is most likely an
asphaltene; it is possibly some simple carbon build-
up but asphaltene is the most likely material type.
The white crystalline material is most likely an
additive of some type that did not completely
dissolve. Copper showing in the metals analysis is ppm not present as a wear particle, suggesting possible ppm passivation or erosion on a copper surface.
Passivation is the most likely suspect with low
amounts of sulfur and phosphorous presence
potentially creating a weak acidic environment that
copper surfaces tend to react to.””
 

andy65

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Causes?
So did fuel recirculate to the tank carrying filter particles?
Asphaltene: Is that from bad fuel?
Additive: Type?
 

c1steve

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Asphaltene would probably be from the fuel breaking down over time.
 

Downrigga

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I highly doubt that white stuff is from a filter. I still say its dead bacteria. It might have shown some filter material trapped in it but im sure its organic.
 

Gene B

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light bulb moment - the FG particulate is probably from prior owner cutting the hand holes in the tank to clean it out
asphaltine form fuel braking down makes some sense as well-the boat is 1998 and the Cummins only has 570 hours
no idea on the additive type- this problem started two owners ago
 

Downrigga

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If fiberglass could turn into that they there would be no such thing as fiberglass tanks. I have been looking at bacteria/fungus etc in fuel all my adult life. Im sticking with bacteria.
 

Gene B

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I meant FG sawdust from cutting hand holes in the top of the tank to access and clean the tank bottom between baffles.
given the low engine time and obvious low use no doubt the fuel collected some bugs at one time.
i plan on giving her a good work out this season!

thanks
 

c1steve

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I would install an Algae-X magnetic fuel conditioner. Running oil past a magnet has several positive effects.

It will clean and polish your fuel a shocking amount, and the asphaltene problem should go away. I have installed many of them, and the results have always been excellent.
 


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