I changed my Cav fuel filter today, and I'm glad I did.
It appears the Black Death has returned.

I had a problem 12 months ago so I drained and cleaned the 100lt tank then added fresh fuel. The motor has been running great since.
Maybe the rough ride last weekend on the way to Lucinda stirred some crap up.

I've been using Fuelmaster additive at twice the recommended ratio since. At $80 for a litre for the stuf I was hoping it would keep the fuel clean, it states it eliminates fungus. Not in my tank it doesn't !

Does anyone else use Fuelmaster ?
Any other brand working for you?

Dont use much motors.

Are you using stale fuel and running it down to empty?

I was taught stale fuel a curse and running a motor close too empty sucks all the **** out of the tank?

I really have no other help....and I rarely use petrol so dont trust a word I say but I hope I helped in some small way

I add it to my Jerry cans and buy on fuel at a service stations that sells volumes of diesel fuel for a start .
Its a pain transporting it but it gives me peace of mind

http://www.supercheapauto.com.au/online-store/products/Liqui-Moly-Diesel-Algae-Stop.aspx?pid=347773&menuFrom=60402#Recommendations
I guess you also have a water trap on your filter system if not fit one

Ive seen new imported earth moving machines not where I work now but with algae in the tanks

Combating uncontrolled growth in fuel tanks
Quote I found below

LIQUI MOLY additives awarded second place in test by German sailing magazine.

There is a whole series of additives on the market, claiming to keep marine diesel germ-free and engines clean. The editors of specialist magazine Segeln wanted to know which products actually keep their promise. Two products from Ulm-based additive specialist LIQUI MOLY were also on board. The Marine Diesel Additive and Anti-Bacterial Diesel Additive were awarded an outstanding joint second place.

When diesel becomes contaminated with water, it makes a perfect breeding ground for bacteria, yeasts, algae and fungi. This can lead to blocked filters and malfunctioning engines - a very likely outcome since the diesel in fuel pumps is never pure. The fuel is far more likely to become contaminated with water while being kept in storage tanks or transferred from tank to tank. Biodiesel additives and condensation in on-board tanks supply a constant food source for germs. To find out what really beats the diesel menace, the editors put seven bacteria killers that are available on the market and one prototype under the microscope as blank tests to investigate their microbe-destroying properties in the microbiology lab of manufacturer Schülke und Mayr.

The results were disillusioning: The specialist magazine wrote three products off as "total failures". The test candidates from Ulm performed far better. "The results for the two LIQUI MOLY products were much more satisfying. The shock dose worked perfectly; nothing survived the chemical attack," wrote the sailing magazine, which hoisted the Marine Diesel Additive and Anti-Bacterial Diesel Additive onto the second step of the podium. Grotamar 71 was awarded first place.

The test was performed as follows: The laboratory ran two test series with the additives: One diesel sample was given a preventive dose of the respective test candidate, while the other was given a shock dose recommended for contaminated diesel.

Famous last wards, but hear goes (touch wood).

Since I cleaned the black death out of my 70L day tank (when I first brought the boat 8 years ago) it has never returned. My keel tank luckily is free of any issues, be it black death or residual crud. My draw pipe in the keel tank is 2mm from the bottom of the tank to make sure I draw out any crud that may (by some miracle )have gotten into the tank. All the fuel I put in the keel tank is put through a Mr Funnel (link below) to remove any water or crud, be it from a gerry can or dock fuel bowser.

And I always keep my Keel Tank and Day Tank full, not 3/4 or 7/8 but full full. This is to reduce the amount of air in the tank and thus the amount of moisture from the air that may decide to condensate inside the tank.

Simple equation: less air in tank = less moisture in tank

The only fuel that goes into the 70L Day Tanks come from the Keel Tank, but has to go through a glass bowl filter (with internal filter element) first. These types of filter are easy to check visually and can be drained easily. I've never had an issues in the last 8 years.

From the day tank the fuels is filtered again (glass bowl below filter element) before going to the final filter on the Yanmar engine.

All fuel has a biocide treatment added at the specified ratio. (I'll need to do a trip to the boat to get the brand) All diesel stored in contains on the boat has the biocide added to the containers. All containers are stored inside the boat in a dry location so there is no chance they can suck in moisture due to temperature changes.

Stale fuel. My story. I had my boat out of the water for 3 years and the 180L of diesel in the (full) keel tank never gave me any issues when the boat went back in the water. I'm not sure how long it takes diesel fuel to go stale or WTF stale even means, but 3 years of sitting in the keel didn't cause any problems. Maybe it's an urban myth. Now petrol mixed with OB oil, that's a different story. (Yes I was a good boy and ran my engine every couple of weeks while the boat was out of the water)

Now, I have been out in over 30knts running the motor to keep the head to wind as I've been putting in another reef and it's probably the best (or worst) conditions for putting your money where your mouth is with regard to testing the management of diesel fuel quality on your boat.

Anyway, that's what works for me. Maybe you can glean something useful from it.


www.mrfunnelaustralia.com.au/buy-online.html

Recently I had some water contamination. I sucked out the fuel with an electric pump that's used to drain sumps and dicarded it. Added 20 litres of fresh diesel with some metho added. Used the boat a few times but still noticed water in the clear bowl. I sucked it out again and discarded the diesel. This time I ensured I sucked up everything off the bottom everywhere. Some of the stuff passing through the clear tube was weird. Put 20 litres of diesel back in and it's now crystal clear. Tank is fibreglass.
As HG02 says buy your fuel from a place with a high turn over and avoid ethanol shops. Local place has ethanol in the diesel, smells sweet!

I buy all my diesel from the service station at the same time I buy diesel for the 4wd. I have never got fuel from the marina.

I am guilty of only filling the tank to 50%.

maybe when I cleaned the tank last year the bacteria survived.

I've emailed Fuelmaster and asked them to explain how their product which states it " eliminates fungus & bacteria" has not worked.

Like HG I buy my diesel from a servo. My tank holds 36 ltrs and is stainless steel. I always keep it pressed.
As Crusoe so rightly said......the less air space..the less water.

Hi, been there done that. I use fuel doctor at the strength required for marine use, run the fuel through a sedimenter thence a raycor 500 primaryfilter then the engine mounted filter.
This is after much filtering of the fuel in each tank via a high volume fuel transfer pump with a high volume 30 micron filter.
So far so good.
Cheers, Bob

Is the diesel you buy from the petrol station 'bio-diesel'?

If yes it will grow algae much quicker than non bio-diesel.

I buy from garage and check extensively that its not bio-diesel but still use an additive.

No problems in over 10 years and fue tank is often only half full.

I had fuel problems until I installed new tanks. The new tanks draw fuel from the bottom so it gets separated at the filters rather than brewing at the bottom of the tanks. I also now have a sump drain valve on each tank in case I get a bad batch of fuel.
I've had zero fuel problems even though my tanks are only half full most of the time.

Until you clear up the ugly concoction growing on the bottom of your tank; the black death will return every time it gets stirred up in some rough weather.

My boat had very dirty fuel when I bought it, unattended for 5 years.

I drained the tank completely and refilled it but there were still traces of that black stuff (whatever it is!) in the CAV filter and drops of water.

I bought a 12v inline fuel pump from Supacheap autos for about $20 and put two CAV filters inline with it. Then rigged up the outlet of the fuel tank (160L) to run through the pump, then the two filters, then back into the tank from the top. The hose entering the top was pushed way in so that the fuel inside the tank would be constantly turbulent due to the incoming fuel. ie. Stir up the bottom.

Then left it going for a couple of days. Eventually the fuel running through the filters was clean. I checked it by decanting some into a glass jar and looking at it in bright light. After that (as with the other guys) I only bought fuel from a servo. and carted it to boat. A pain. But problem never came back. Until one of my crew accidentally put petrol in instead of diesel and I had to drain and replace it all again :-)

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samsturdy said..


Like HG I buy my diesel from a servo. My tank holds 36 ltrs and is stainless steel. I always keep it pressed.
As Crusoe so rightly said......the less air space..the less water.

That stops or reduces condensation. The water will still gather at the bottom of the tank and eventually will get sucked up to the filters/fuel separator. The unfortunate bit is the water usually comes from the bowser. When the fuel trucks deliver the fuel to the stations sometimes they deliver petrol and the next delivery might be diesel. The truck driver flushes through with water between loads and sometimes they are not that well drained and the next load gets contaminated. This info is from one of the truck drivers delivering diesel to the fishermans wharf commenting on some of his slack mates.
Treks method of cleaning the fuel is called polishing and it's OK if you have large amounts of diesel. My tank holds 40 litres and gets filled twice a year. Boat is sailed one a week all year so diesel costs are not all that high. The old diesel I brought home to clean engine parts so it's not completely wasted.

I don't buy Bio-diesel I issue BP ultimate which I believe to be the best diesel available, certainly makes the 4WD run better

My SS tank is set up with a fall to one corner where the pick up point is located 75mm up from the bottom. I've started draining off diesel from that low point once a year so water / crap doesn't build up and reach the pick up point.
That's the problem I had last year the crap at the bottom of the tank hadn't been drained off for many years and it reached the pick up point and was sucked into the motor.

Maybe the black crap on the filter is from Fuelmaster killing off the remaining bacteria in the fuel lines and sections of the tank I couldn't reach to clean. I'll replace the filter again in 3 months to see if it's still present.

The ideal fuel tank is one with a sediment well with drain cock below the fuel pick up.

In the '80's the fish co op had underground diesel tanks alongside the wharf and we used to fill our boats from that. It was the old style diesel not the highly refined road diesel we all use now. I never had a problem with fungus but the large trawlers did and would often have to change filters at sea. The filters used to block up with this sort of glutinous semi clear stuff about the constancy of dessert jelly. The black stuff in the photo above looks like dead fungus and looks the same as the stuff I sucked out of my tank a few weeks ago. I treated my diesel with some metho before emptying the tanks the second time. I sucked up nearly everything out of the tank and when I refilled the filter bowl stayed clean.
Today after I came back in from sailing I checked the filter and there is at least 10mm of black crud in the bottom of the bowl with crystal clear diesel above. Must have been enough metho left to sort it out. Another filter change is one the cards. Fortunately they are incredibly cheap, just annoying to change.

I spoke to Fuelmaster today and they said the black crap on the filter was dead bacteria properly from the shock dose of Fuelmaster I added to the diesel after cleaning the tank as " it was impossible for the bacteria to survive" if using Fuelmaster

They recommend I change the filter again in 3 months to check if bacteria was still present.

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Ramona said..
Today after I came back in from sailing I checked the filter and there is at least 10mm of black crud in the bottom of the bowl with crystal clear diesel above. Must have been enough metho left to sort it out. Another filter change is one the cards. Fortunately they are incredibly cheap, just annoying to change.

How did the black crud get into the bowl past the filter? My bowl was clear just crud on the filter.

The fact is - according to an independent expert - that the petrol companies used 3% bio component in their product until recently. New levels have been agreed recently, 12%, which is causing problem for small time users who store their fuel for a considerable period. The multis did not fanfare this change, whoever green it might sound.
I was running a fleet of trucks for years and we had some serious problems but those problems related to the chemical components is some fuels from some smaller suppliers usually originated in Queensland. Had a court case won by us when in one case the chemical analisys returned such result, that the copper content was 1200 times the normal! We never had filter clogging problems though. Our tanks got emptied every second day and fully filled. Condensation water was not an issue, dayly checking the fuel system, the sedimentor drained as well.
We are talking about diesel fuel of course.
In yachts, the 3% bio component seldom caused problems, hence the bio-treatment which has rid of it in most of the cases. In the new fuel, with 12% bio component almost silently introduced, is going to cause problems for many more customers because the 'shelf time' of this new concoction is much shorter and needs much more radical treatment to keep the mixture in good order.
So here we are. You better fill up from busy bowsers at reputable suppliers who could give you a chemical analisys if asked nicely. I do not fill up, never filled up and never plan to fill up at marinas. I rather pay a taxi fare to the next busy bowser.
The most recent experience of mine in the fuel wars, and this time is petrol, happened when my bike started running like a bronco, not starting and other symptoms of bad fuel after regularly using this total crap called E10. When l pulled down the carburettor l found brownish coloured deposit all over the inside of the body which is according to my engineer friend is from the E10 fuel's alcohol and additive component. On the top of this, l found all the rubber bits -O rings, seals - in a state of severe disintegration. All of them were ' marsh mellowishly' soft, almost kneedable like blue tac. I filled up irregularly and kept the fuel for a long time, not u
sing the bike often. This days only using 95 unleaded exclusively.
The tank on the yacht is fine, just checked it. Using the green stuff from Whitworths works for me. Touch wood!

Rest at ease, you are not going to be served with a reliable product, whatever you buy.

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seabird said..
I spoke to Fuelmaster today and they said the black crap on the filter was dead bacteria properly from the shock dose of Fuelmaster I added to the diesel after cleaning the tank as " it was impossible for the bacteria to survive" if using Fuelmaster

They recommend I change the filter again in 3 months to check if bacteria was still present.

Ramona said..
Today after I came back in from sailing I checked the filter and there is at least 10mm of black crud in the bottom of the bowl with crystal clear diesel above. Must have been enough metho left to sort it out. Another filter change is one the cards. Fortunately they are incredibly cheap, just annoying to change.

How did the black crud get into the bowl past the filter? My bowl was clear just crud on the filter.

The black layer on the bottom is just fine particles not the grassy looking stuff in your filter. I have not pulled it off yet to clean. Most of my crap I sucked out through a clear plastic tube.

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Ramona said..
In the '80's the fish co op had underground diesel tanks alongside the wharf and we used to fill our boats from that. It was the old style diesel not the highly refined road diesel we all use now. I never had a problem with fungus but the large trawlers did and would often have to change filters at sea. The filters used to block up with this sort of glutinous semi clear stuff about the constancy of dessert jelly. The black stuff in the photo above looks like dead fungus and looks the same as the stuff I sucked out of my tank a few weeks ago. I treated my diesel with some metho before emptying the tanks the second time. I sucked up nearly everything out of the tank and when I refilled the filter bowl stayed clean.
Today after I came back in from sailing I checked the filter and there is at least 10mm of black crud in the bottom of the bowl with crystal clear diesel above. Must have been enough metho left to sort it out. Another filter change is one the cards. Fortunately they are incredibly cheap, just annoying to change.

Hi Ramona. When I bought my boat I discovered my filter was full of that semi clear jelly stuff.
I shocked the tank with fuel treatment and changed the filter and that seems to have cured it.
But I'm interested in what the jelly was......any idea????.

Select to expand quote

samsturdy said..

Ramona said..
In the '80's the fish co op had underground diesel tanks alongside the wharf and we used to fill our boats from that. It was the old style diesel not the highly refined road diesel we all use now. I never had a problem with fungus but the large trawlers did and would often have to change filters at sea. The filters used to block up with this sort of glutinous semi clear stuff about the constancy of dessert jelly. The black stuff in the photo above looks like dead fungus and looks the same as the stuff I sucked out of my tank a few weeks ago. I treated my diesel with some metho before emptying the tanks the second time. I sucked up nearly everything out of the tank and when I refilled the filter bowl stayed clean.
Today after I came back in from sailing I checked the filter and there is at least 10mm of black crud in the bottom of the bowl with crystal clear diesel above. Must have been enough metho left to sort it out. Another filter change is one the cards. Fortunately they are incredibly cheap, just annoying to change.

Hi Ramona. When I bought my boat I discovered my filter was full of that semi clear jelly stuff.
I shocked the tank with fuel treatment and changed the filter and that seems to have cured it.
But I'm interested in what the jelly was......any idea????.

Fungus.