Diesel fuel woe

WestWittering

WestWittering

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Can anyone tell me what this is?

Left the boat standing for a 'good while' and returned to a tank of jelly. The engine ran for a while, then the filter blocked and the fun began. The fuel was pumped out, tank removed and cleaned out. Refilled with 'road' diesel. Three weeks later, we are back to square one. I'm going to get a new plastic tank, but in the meantime, what is this? It's quite gritty, the crystals are square and the last batch tasted sweet. I thought it might be crystallisation of the fuel, but we haven't had the weather conditions or the time for that. Could it be glycerine?


IMG_0571.jpg
 
WestWittering said:
Can anyone tell me what this is?

Left the boat standing for a 'good while' and returned to a tank of jelly. The engine ran for a while, then the filter blocked and the fun began. The fuel was pumped out, tank removed and cleaned out. Refilled with 'road' diesel. Three weeks later, we are back to square one. I'm going to get a new plastic tank, but in the meantime, what is this? It's quite gritty, the crystals are square and the last batch tasted sweet. I thought it might be crystallisation of the fuel, but we haven't had the weather conditions or the time for that. Could it be glycerine?


View attachment 64580
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Does someone not like you? Looks like the old sugar in fuel tank trick!
Stu
 
It is almost certainly a microbial infection caused by contact with contaminated water. Occurs in diesel and gasoline from time to time. A good fuel treatment product should fix it but absolutely everything should be cleaned out and sterilised before refilling.
 
vyv_cox said:
It is almost certainly a microbial infection caused by contact with contaminated water. Occurs in diesel and gasoline from time to time. A good fuel treatment product should fix it but absolutely everything should be cleaned out and sterilised before refilling.
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I tried Marine 16 on the sample & it had no effect. The granules did not disolve and the tank was thoroughly cleaned & sterilised the first time. I can't find anything on t'interweb that looks like that....
 
WestWittering said:
I tried Marine 16 on the sample & it had no effect. The granules did not disolve and the tank was thoroughly cleaned & sterilised the first time. I can't find anything on t'interweb that looks like that....
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Google 'diesel fuel jelly'. You'll find a few, one is an old ybw post from 2011. Not to be confused with cold weather gelling or 'conventional' bug.
 
Looks like sugar, tastes like sugar?
I've seen what it does to a petrol tank, not sure how it reacts with diesel.
 
I'll go and take another sample and if it dissolves in hot water, then it probably is sugar..... But if it is, then WTF? There is no way I have caused offence to anyone to that degree! I'm amazed TBH...
 
I can't imagine any lifeform producing crystals like that in such a short time. My first reaction on seeing your first photo was that it is salt caused by some kind of leak into the diesel tank. However, if it tastes sweet then I'm sure it's sugar which, as you say, is amazing. :(

I don't think that there is a simple test for sucrose so your warm water test is probably as good as anything.

Richard
 
WestWittering said:
I'll go and take another sample and if it dissolves in hot water, then it probably is sugar..... But if it is, then WTF? There is no way I have caused offence to anyone to that degree! I'm amazed TBH...
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Disconnect your fuel filling pipe and put something over to seal it. You'll then see whther it forms spontaneously in the tank or is dropped in.
 
vyv_cox said:
It is almost certainly a microbial infection caused by contact with contaminated water. Occurs in diesel and gasoline from time to time. A good fuel treatment product should fix it but absolutely everything should be cleaned out and sterilised before refilling.
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I would have said a bug but with him saying recently taken the tank out and cleaned etc turned me towards contamination with sugar.
Stu
 
Given that they look like colourless cubic crystals and are only likely to be either sugar or salt you could try to see which. If you heat sugar enough it will melt and caramelise then burn. You will get a nice caramel smell. Try a bit on silver foil over a candle flame. If you put salt in a flame it will glow orange like a sodium lamp but it's difficult to get it hot enough. Sugar melts much faster. Try some from the kitchen first to get an idea.
 
Also is there any chance the fuel cap is leaking (check the seal) and also possible that sea water has got in? Have you been beating with the rail under?
 
RichardS said:
I think the OP's taste test was reasonably conclusive in differentiating between sugar and salt. :)

Richard
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Fine, but he wanted to know if it was sugar and that's a fairly conclusive easy test. Of course there are better ones but not with household products. Antifreeze tastes sweet too of course.
 
ip485 said:
Also is there any chance the fuel cap is leaking (check the seal) and also possible that sea water has got in? Have you been beating with the rail under?
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Of course you'd also have to have large quantities of sea water evaporate rapidly after leaking in to leave that much salt behind in such a short period.
 
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