Fuel contamination

[Fr J Hackett]

Having changed engine and fuel sytem over the winter which definitly included complete replacement of previous fuel with 200 L of white bought from a supermarket and suposedly the tank was cleaned ? after some 30 hours of motoring followed by a twelve hour thrash to windward I find that my primary fuel filter is blocked and after settling and then draining a litre off the tank sump there were small brown / black globules in the diesel but definitly no water. I shall drain again in a couple of weeks when I go out to the boat but the questions are what is the contamination, biological or asphaltines, can it be removed quickly or progressivly what treatment would the forum use both initally and ongoing, answers please.

 

[benlui]

I had the same issue exactly, and it took a complete flush of the tank and i used diesel cleaner. What you have in your tank i think is whats known as diesel bug. Its a fungi that lives between water and diesel. Once you treat the diesel, it should run its course after a tank or so.

 

[ms1]

Probably bug, you dont necessarily see loads of water. If you can get into the tank via an inspection hatch or by removing the fuel gauge sender unit you can do quite a good job removing the contamination by'hoovering' round the bottom of the tank with a bit of tube and a hand suction pump. if you can get rid of the worst of it then treatment should be more successful.

 

[William_H]

It sounds like from your post you have a good sump drain. ie a drain from the bottom of the tank. If you reckon this drain will empty from all the bottom of the tank. ie the tank bottom is not flat/level then you can perhaps clean the tank successfully by draining from the sump. This should be done after 24hrs of settling time with no agitation.

You can drain the whole tank or just enough until you get clean samples. Put the fuel into a tall container, glass is great so you can see the fuel but you may have too much fuel. Allow the fuel to settle in the container for 24 hours then siphon off the top portion which can be used again. Discard the bottom dirty part.
How much you drain and how much you discard depends on how serious you are about good fuel.
Monitor and clean fuel filters frequently and as suggested use a fuel cleaner or biocide.
The bug is called Cladisporan Resinae and afflicts gas turbine aircraft (jets that burn kerosene) Jet fuel often has biocide added as a matter of course. Obviously for heavily used aircraft it is not so much of a problem. The bug grows in the water content of the fuel.

good luck olewill

 

[angelsson]

Having changed engine and fuel sytem over the winter which definitly included complete replacement of previous fuel with 200 L of white bought from a supermarket and suposedly the tank was cleaned ? after some 30 hours of motoring followed by a twelve hour thrash to windward I find that my primary fuel filter is blocked and after settling and then draining a litre off the tank sump there were small brown / black globules in the diesel but definitly no water. I shall drain again in a couple of weeks when I go out to the boat but the questions are what is the contamination, biological or asphaltines, can it be removed quickly or progressivly what treatment would the forum use both initally and ongoing, answers please.

Make up your own fuel polishing system, keeps fuel clean before it ever gets near a primary filter