Fuel bug!

[Travelling Westerly]

I'm pretty sure I have/had a case of fuel bug but not sure how to get rid of it...

History to present day:

When I bought the boat I found a convenient sump with a ball valve fitted on the diesel tank so I drained off some fuel and found at least 1L of water in the tank! Boat had been sitting around on the hard for about a year and prior to that had extensively cruised South America.

I fitted a Racor 900 series duplex filter set up (complete overkill but had a brand new set up kicking around so why not use it). I then plumbed in a Racor 500 filter to the fuel tank sump and into the fuel return line so can polish as required.

I treated the tank to fresh fuel, shock dosed with Marine 16 several times over the next year and used Marine 16 total during most fill ups.

Ive checked the deck filler O ring and ensured no gross water is getting into the tank external breather, all good so far.

A year after fitting the 900 series filter assembly I did a filter change. It was bad, coffee type hard deposits in bowl, filter black with grease like substance on element. New filter fitted and continued on.

I switch the polisher on every few weeks and it often knocks out string like black stuff that settles into a black oil in the bottom of the filter bowl.

Ive put 300 hours on the engine last year and today I changed the primary 900 series 10 micron filter again. This time there was still coffee grinds hard deposits in the filter bowl but the filter element was much better. It was still dark but no where near as much sludge. When I say sludge it looks identical to brown grease! It feels very slippery to the touch and if you put it into diesel solution it turns to black into a oil like substance.

I cant gain access to the tank internals even though there is an access hatch on top of the tank as the cockpit floor is 5cm above the tank, good idea that was!

My questions are is this bug, if so will continuing to dose tank and polish the fuel fix it long term or is this brown grease like substance possibly FAME being knocked out and captured by the Racor 10 micron filter element?

As I understand it without water in the fuel/ tank the bug can't live. As I polish very often there is no water in the tank, even condensation is removed when I carry out a polish cycle.

 

[boatmike]

Yes its bug. No you wont eradicate it unless you drain and clean the tank. Many people will tell you that treatments and polishing are sufficient on their own. mostly these people have never had a serious contamination themselves. Unfortunately the stuff falls to the tank bottom and stays there until you go to sea and stir it all up so stationary fuel polishing is not going to clear it. Marine 16 is great for prevention and will help clear mild contamination when its in solution but killing the bug is only the first step. removing the residual crud is the problem and the only really effective solution is to cut an access hatch in the top of the tank and manufacture a closure that can be sealed with sikaflex or a gasket. Once cleaned Marine 16 or similar is a great prevention. And while it is great to eliminate the water that won't cure the problem on its own. Its worth asking how that much water got in there in the first place though. It sounds a lot to have been caused by condensation alone........

 

[Sandy]

.

You might find the above thread answers your questions.

 

[Travelling Westerly]

You might find the above thread answers your questions.

Yeah, spotted that thread after I posted mine thanks.

Id still like to know if the brown grease could be FAME knock out though.

Im still thinking no water in tank means no active fuel bug though in which case polishing would eventually clean up the tank especially as the boat is constantly on the move so the fuel is always moving around?

 

[William_H]

OP says that the tank has a drain cock at the bottom. That is good but we must ask the question about the shape of the bottom of the tank. If it is flat then water and bug can still lurk in corners or low side. Ideally a deep vee or cone shape would ensure bottom drain gets every thing but is not common. So fuel polishiong and in fact fuel usage will only get fuel and crud from the area around pick up. Is there a lot of water crud bacteria still remaining? That is the question.
As said the only answer is to get access to the top inspection hole and open it up. Mop out all fuel water crud or better still remove tank and steam clean it upside down. But as with so much in boating it all depends on your own dilligence and you must decide what to do about it. Twin filters I presume this means alternatively select able filters would hopefully get you out of trouble for a time if engine does grind to halt with contamination. As said treatments are not a cure in them selves but must help keep a clean tank clean. ol'will

 

[KompetentKrew]

I believe the brown snot is the bug, not the "coffee grinds hard deposits" - not sure what the latter are. Is it a steel tank? Could it be rust?

 

[38mess]

Could you be filling up with bad fuel?

 

[Travelling Westerly]

OP says that the tank has a drain cock at the bottom. That is good but we must ask the question about the shape of the bottom of the tank. If it is flat then water and bug can still lurk in corners or low side. Ideally a deep vee or cone shape would ensure bottom drain gets every thing but is not common. So fuel polishiong and in fact fuel usage will only get fuel and crud from the area around pick up. Is there a lot of water crud bacteria still remaining? That is the question.
As said the only answer is to get access to the top inspection hole and open it up. Mop out all fuel water crud or better still remove tank and steam clean it upside down. But as with so much in boating it all depends on your own dilligence and you must decide what to do about it. Twin filters I presume this means alternatively select able filters would hopefully get you out of trouble for a time if engine does grind to halt with contamination. As said treatments are not a cure in them selves but must help keep a clean tank clean. ol'will

The tank has a sump, a proper catch sump lower than the floor of the tank. Its a well thought out stainless tank with an access hatch on top, just no way of getting to it unless I cut through the cockpit floor.
There is no water in tank at all the polisher, Racor turbine 500 filter, removes any build up from condensation if it gets cold.
I think its getting better as there was not nearly as much debris in the filter this year. Just this brown grease. As the filter is way over spec size wise it has never blocked and the filters unit dp gauge shows no huge pressure drop with engine under load.

 

[Travelling Westerly]

I believe the brown snot is the bug, not the "coffee grinds hard deposits" - not sure what the latter are. Is it a steel tank? Could it be rust?

I had a look on Google and a few fuel businesses said the hard coffee grinds was an indication of bug. Im just not sure if mine is left over from a past case of infection in which case my filter system and polisher should mop it all up?

 

[Travelling Westerly]

Could you be filling up with bad fuel?

I'm thinking possibly in the past before my ownership.
I always use a Mr Funnel with the water filter built in when I top up and dose with Marine 16 total.

 

[Biggles Wader]

If you cant get access to the tank to clean it the sump is the next best thing. I would run the tank down to nearly empty and drain the rest via the sump. See what comes out and do it fairly regularly. Hopefully that will clear the debris.

 

[Refueler]

Yes its bug. No you wont eradicate it unless you drain and clean the tank. Many people will tell you that treatments and polishing are sufficient on their own. mostly these people have never had a serious contamination themselves. Unfortunately the stuff falls to the tank bottom and stays there until you go to sea and stir it all up so stationary fuel polishing is not going to clear it. Marine 16 is great for prevention and will help clear mild contamination when its in solution but killing the bug is only the first step. removing the residual crud is the problem and the only really effective solution is to cut an access hatch in the top of the tank and manufacture a closure that can be sealed with sikaflex or a gasket. Once cleaned Marine 16 or similar is a great prevention. And while it is great to eliminate the water that won't cure the problem on its own. Its worth asking how that much water got in there in the first place though. It sounds a lot to have been caused by condensation alone........

Partly true ...

Although you cannot eradicate it - despite some posts on other t5hreads by some ... you8 CAN control it. For the operation I will describe - forget about Polishing and using that gear ... its a waste of time.

First is to give a really good dose of ENZYME based additive. Leave to action for a day. Then drain down the tank as best you can ... then get a siphon kit - Pela is excellent for this. Get as much 'bottom' out as possible.

Its good to use the fuel you took out to try slosh about or stir up bottom while siphoning.

OK - so now you have containers of contaminated fuel. We will save as mucxh as possible of that ... no need to dump it.

Let it stand .... the additive you put in wilol still be working. As the fuel clears - you will see crud collecting at bottom. When fuel is clear - then decant carefully trying not to get crud transferring as well.
Once clear fuel is in next container - dose that clear fuel again. The crud goes to whatever fire you can dump it to !! You can flush out the container after and re-use as we are adding additive as we go ...
Let clear fuel stand again. Maybe you get some more crud settle ... basically you keep repeating till its basically zero crud settling.

Now you have treated clear fuel ... you can put back to tank - with again a dose of EXZYME additive ... M16 is NOT ..... Any of the Startron / Soltron etc. Enzyme based are best for this .... (I am not saying only those - as there are many on the market and its just common names people know).

You will remove ALL filters of course ...... pulled treated fuel through to clear any crud in the lines. Cleaned filter bowls and new filters .... a Volvo Truck trick here is to dowse filters in additive (Volvo actually say to fill the filter bowl with it ... that's a bit OTT !!).

Bleed system ... and start engine.

Lets put fact to fiction ... Polishingh has NO benefit in treating or controlling Bug whatsoever. All you are doing is filtering crud out of the fuel .. whether its dead bug or sediments. Its far more effective to use an additive on regular basis .. I prefer Enzyme based as then dead bug and any water is dispersed and burnt in the engine.

It may surprise - but I have had 2 dead engine events due to bugs ..... both due to Diesel I added to my tank without dosing ..... I had ru8n out of additive ... and stupidly assumed it would be fine .... Both times took about 2 days after fill up to do the dirty on me. !!
Repeated change of filters got me going enough to get into harbour and new supply of the additive. Strong dose .. new filters and away we went.

That was over 10yrs ago .... and I have not drained or siphoned out my tank since then .. I have diesel sits in tank over winter ... but I am religious about my additive... Enzyme based ...

 

[Refueler]

Yeah, spotted that thread after I posted mine thanks.

Id still like to know if the brown grease could be FAME knock out though.

Im still thinking no water in tank means no active fuel bug though in which case polishing would eventually clean up the tank especially as the boat is constantly on the move so the fuel is always moving around?

No it is not FAME. 'New' dead bug is usually in form of a gel like paste ... as it ages - it dries and hardens.

 

[Refueler]

Could you be filling up with bad fuel?

ALL diesel / Kero has potential for bug.

 

[38mess]

ALL diesel / Kero has potential for bug.
[/QUOTE
And to bulk up their tanks with water

 

[Refueler]

Just a comment - post usually should be outside the quotes ... I've noticed more and more that posts have been made inside the quotes ...

Anyway ... for many years - Terminal product tank bottoms had water used as a bottom layer to 'seal' .... but later it was discontinued except where old tanks may still be in use - rare today.
That is LARGE Terminals ... not truck distribution storage.

 

[mil1194]

I'm pretty sure I have/had a case of fuel bug but not sure how to get rid of it...

History to present day:

When I bought the boat I found a convenient sump with a ball valve fitted on the diesel tank so I drained off some fuel and found at least 1L of water in the tank! Boat had been sitting around on the hard for about a year and prior to that had extensively cruised South America.

I fitted a Racor 900 series duplex filter set up (complete overkill but had a brand new set up kicking around so why not use it). I then plumbed in a Racor 500 filter to the fuel tank sump and into the fuel return line so can polish as required.

I treated the tank to fresh fuel, shock dosed with Marine 16 several times over the next year and used Marine 16 total during most fill ups.

Ive checked the deck filler O ring and ensured no gross water is getting into the tank external breather, all good so far.

A year after fitting the 900 series filter assembly I did a filter change. It was bad, coffee type hard deposits in bowl, filter black with grease like substance on element. New filter fitted and continued on.

I switch the polisher on every few weeks and it often knocks out string like black stuff that settles into a black oil in the bottom of the filter bowl.

Ive put 300 hours on the engine last year and today I changed the primary 900 series 10 micron filter again. This time there was still coffee grinds hard deposits in the filter bowl but the filter element was much better. It was still dark but no where near as much sludge. When I say sludge it looks identical to brown grease! It feels very slippery to the touch and if you put it into diesel solution it turns to black into a oil like substance.

I cant gain access to the tank internals even though there is an access hatch on top of the tank as the cockpit floor is 5cm above the tank, good idea that was!

My questions are is this bug, if so will continuing to dose tank and polish the fuel fix it long term or is this brown grease like substance possibly FAME being knocked out and captured by the Racor 10 micron filter element?

As I understand it without water in the fuel/ tank the bug can't live. As I polish very often there is no water in the tank, even condensation is removed when I carry out a polish cycle.

This is bug….it needs cleaning. I hold 3600litres. I’ve ‘cured it’ so if you want to ask me then please feel free.

 

[Travelling Westerly]

This is bug….it needs cleaning. I hold 3600litres. I’ve ‘cured it’ so if you want to ask me then please feel free.

Wow thats a lot worse than mine. My filters look nothing like that but the bowl stringy contents look similar only mine are a little smaller.
I think my bug infection may be dead and Im just filtering out the debris left over now?
How did you manage to clean it out?

 

[Refueler]

I shall say it again ...

You CANNOT CURE the Bug .....

You can only control it.

 

[Marceline]

this new video from Mike from Sailing Cos I Love It was really helpful (as are so many of his videos) in understanding it - especially for beginners like myself

Youtube - Sailing Cos I Love It