Diesel Bug in Fuel Tank. How to clean the fuel tank

[Zhivili]

We have a black slime which blocks the filters etc. Everyone tells me its Diesel Bug. I have removed the tank and fitted new fuel lines. Am trying to get a new tank, but looks like I will be cleaning existing. How do I clean the tank ? We have had this in the past and I want to get rid of it for good. I truth thought a new tank and new fuel lines would solve the entire problem, and have ordered a new tank from Ancasta. New tank hasn't arrived yet - hence thinking of cleaning the old.

 

[Evadne]

You can get the tank steam cleaned, but as you say it is not the only component that needs cleaning. The bug will be present in the fuel lines at least as far as the first filter and they'll need cleaning out or replacing as well.

Even with every bug removed, you'll need to prevent it happening again: the bacteria are present in some if not all fuel vendor's tanks, and if you picked it up once then the chances are you will pick it up again.

Draining off the water is an important thing to do regularly as it lives at the interface between the water and fuel. There are various biocides on the market, I tried a "standard" one with limited success, but started using one of the enzyme based ones, Soltron, and have not had many problems since. I also only use garage-bought diesel, unless there is no choice, but that is not always a sensible option if you have a big engine.

 

[LeytonC]

yes, you need to keep the fuel treated as it will be passing through components and fuel lines that might be contaminated, and then (in most systems) some of it is passed back to the tank through the injector leakoff rail - with a chance of returning live bug to the tank.


I totaly agree with Dave_White about his choice of fuel treatment!!!

(see link in my signature /forums/images/graemlins/wink.gif)

 

[Evadne]

/forums/images/graemlins/smile.gif thought you might!

 

[irawnsley]

Had the same problem with a Contessa 32, removed the tank, emptied it and washed it out with soapy hot water, allowed it to dry and fitted an L140 de bug unit direct into the fuel line. Never had a problem since. Go to http://www.morison.com.au/units.htm
Can't remember where we bought it form but it was around £70. Bargain!!!!

 

[Topcat47]

I call it the black death. However clean your system is, you can import it in dirty fuel. It's worse than water IMHO, and I've had boat deisel with high water content too. Actually this situation is worse where the deisel is contaminated with water. I use a biocide every second tankful. Getting caught once was enough (I steam cleaned the tank after draining it and then added a double dose of biocide to a gallon of diesel just to make sure any contamination in the return line was dealt with). It worked for me.

 

[pjs100]

Following a bug problem I cut the tanks open scraped & steamed cleaned, renewed the fuel pipes and filters then fitted a Diesecraft system.
I've not treated with biocide and have had no trouble since. I drain down water from the centifuge before every start.
JJTOP

 

[diesel bug hunter]

Diesel Bug Experience
A friend of mine recently bought a fuel polishing machine, as a start up part time business, to top up his retirement income while living aboard his narrow boat.
There was immediate interest and a small queue of boat owners wanting to see it at work and the results.
Here is what happened....... The first call out was by the Severn Estuary pilots who had to tow back a boat that had suffered an engine failure trying to get from Sharpness to Bristol, down the Severn. Water and diesel bug was removed (all witnessed by a small crowd of onlookers) and followed by a recommendation by the pilots to have fuel polished before exiting the lock
See - http://www.gloucesterpilots.co.uk/services/leisure/
The word spread quickly and a succession of narrowboats bound for Bristol via the Seven Estuary soon appeared. Results were mixed. Some had perfectl fuel (the sludge, water and other debris is held in glass bowls on the machine, and is very visible to see) while others had a leaf !!!, water, diesel bug (recognisable as a watery slime that appears between the layer of water and diesel in the glass bowl) and rust flakes.
The most memorable, though, was 15 gallons of water removed from the fuel tank before the machine drew air, as no more liquid was left. A fill up with diesel from a gerry can and the process continued. Emulsion then filled the bowls, looking like a milky cream. The owners of the boat had arrived from the River Severn (tidal and subject to the famous Severn Bore) before the engine cut out in the marina a short while after mooring up.
The boat is now motoring around happliy, but it could have been a disaster if the timing was different.
Conclusions
Boat owners that refill their tanks regularly, and keep them as full as possible (to reduce the effects of water condensation due to temperature changes) seem to have the cleanest fuel.
Tanks left unused for prolonged period get condensation which sinks to the bottom of the tank.
The new "lower sulphur" diesels absorb more water than the old higher sulphur conten types (EEC regulations to blame for this).
Fuel suppliers now must sell through an intermediary (so i have been told) and the intermediary gives the end seller i.e. Asda etc. the option to alter the percentage of biocide (which lowers their buying price) and enables them to compete. I biocide diesel can break down after only 6 months, i've been told (and read) so separation and microbial growth just love Biocides!
I have also been told that this overall situation is becoming worse. A good example being a factory awaiting a late delivery of metal stock onboard the latest high tec transportation lorry, was delayed due to having to fill up on route at a supermarket fuel station and breaking down when the diesel injectors couldn't handle the new diesel blend. Another being a night shift "polishing" the diesel fuel in the bus and coach station after a succession of breakdowns on their coach and bus fleet during long runs requiring tip ups away from base.
Recommendation
Have the existing diesel fuel "polished" to remove water, diesel bug and assorted invaders ... then add some diesel bug preventative chemical to kill all microbes.
Polich the fuel on a regular basis (as it only takes a fill up from a bad source to import water and other crud), keep the tank full and keep pouring in some preventative additive.