Seeking ideas
This is the only access I have to the keel tank, I know it's needs a clean. Plan is to stick a copper tube down there and suck out the sludge as best as possible. Hardly a guarantee of getting it all. Any other ideas someone may have would be appreciated.

I had a tank professionally cleaned ONCE !! They came along and said is the tank empty. Yes.
Great the guy said and stuck a hose in the tank. Half filled it with water and a magic product, looked and smelt like liquid soap to me. Sucked it all out, this is where the expensive part is. They had a truck with pump etc and took it away. Dont put fuel in there for at least 1 week, gave me a big bill and walked off.
Ever since I have flushed my tank with water and wet vacced it out. Obviously making sure it is bone dry before putting fuel back in. Might not be so easy in your situation if you don't have an inspection hatch!

Suck all the fuel out you can and dump it. Add 10 litres of diesel or so with the snake oil of choice. Rig up a fuel polishing system. I use a 12v diesel pump, about 15 dollars off eBay and a Chinese copy of a Racor 500 and cheap paper filters. Just recirculate the fuel for a couple of hours and have some clear pipe to monitor the gunk. In my case I dumped the second lot of diesel but you can suck it out again and let it settle the water and crap out. I just added fresh diesel and wrote off the diesel I just polished. Actually I gave it to my mate and he added it to his cooking oil in his van!

At the risk of blowing yourself up, I have add success with a Becksen hand pump (very gently) it has reducing attachments, certainly very good at picking up debris in the bottom of the tank.
It is amazing how much crap comes when you refill from bowsers.
Throw the diesel away.
If the problem in bacteria then I do as Romona says.
I go to Repco, buy a carton of filters (CAV in my case) and let it rip, when I buy a new boat.
As for normal, I wait until Supercheap has Dieselpower on special and go in and buy a few cartons.
I get funny questions from the staff.
All up we are running 5 diesels at present (plus 2 4WDS) only 3 have I had control of the boat tanks previously.
But I am a fanatic with fuel cleanliness.
I have just started using the new Dieselpower with biocide in one boat so stay tuned.
If you have not motored for several days non stop you will be surprised how warm the fuel in the tank gets because of the return line.
One boat had the tank under the Nav station table so you could warm your feet when it was cold.

Bloke I knew did all the stuff and eventually found the cochroach wing that was on his feul pick up.

Thanks for the tips, I wasn't sure whether to try and polish the existing fuel or just get rid of it, thinking now I will get rid of it and go through the steps as advised. Thanks again.

I did same thing Ramona said a while back. I suggest feed the output of the filtering back into the tank via stiff hose. Then poke that hose down until its bouncing off the bottom of the tank. The idea being that the diesel being pumped back in hits the bottom of the tank with some pressure so stirs up the sludge on the bottom and generates lots of circulating currents. And I used clear hoses to I could see when it was finally clean.

Sediment doesn't just settle on the bottom of the tank. Last boat I bought had black film & streaks of gunk in the filter. Opened up tank inspection port - gunk/gel all over the diesel intake tube and sides. The tank had baffles so couldn't be effectively cleaned. Outcome was a new tank. Not so easy for you, but maybe in area under the picture there's space to drill out an inspection/cleaning port? God luck with it!

This old forum topic may have some helpful advice, cheers

www.seabreeze.com.au/forums/Sailing/General/Black-Death-is-back?page=1

Been at the Raceboard Nationals all week but back to Wapiti today to deal with the fuel tanks

Emptied the Starboard tank today, good access to this tank so it will be easy to clean.

Just need to get a rag in there to get the slime off the bottom, it was pretty bad, enough black slime came out to fill a milk bottle


I am thinking I will just run the engine and genset off this tank as I know it will be clean whereas the keel tank will probably still have this mess on the bottom once its emptied, although I will do my best to remove as per previous advice. I may just use the keel tank as storage in future and transfer from it as required via the racor filters.

Where do you dipose of old diesel, I will have over 200 litres by the time I am done. Maybe I can sell it for 50c a litre.

Give it away to someone who makes fuel from used cooking oils!

Decided to go over the entire fuel system, lines were getting brittle and clamps failing etc. Also checking for any blockages. Found one.

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cammd said..
Decided to go over the entire fuel system, lines were getting brittle and clamps failing etc. Also checking for any blockages. Found one.

Luverly.

What amazed me was when I learnt that is bacteria! It had just been fuel sludge for so long. Bacteria that grows in diesel??? And we can't find a green answer to fuel!
Again the reasons you have mentioned is why the company i used years ago washes tanks with fresh water and detergent. You flush the whole system and dirty water is easier/cheaper to dispose of than diesel. They looked into selling it but it wasn't worth it.

I got a quote for a professional to sort it, aside from the outlay I was keen to sort it myself.

Planning to go extended cruising in few years so I want to be across all systems, the fuel system on Wapiti is a bit complicated. Two tanks, an engine and genset, feed and return lines to each plus two separate manifolds, one to select which tanks feed and the other to select which tank to return fuel to. Most of those lines all meet in the engine room near the primary filters. The system was a bit of a mystery to me prior to the blockage occurring. Now I know every fuel line, where It starts and stops and which way fuel flows through it. I have replaced most of them now, I know all the hose clamps are good, I found a couple of leaks in the process and sorted them, I re routed some lines to make them neater and I can move fuel freely through the circuit using the pumps so I know it's clear of blockages. It's been a dirty job and I still have the keel tank to sort but I have learned heaps. Wapiti is just giving me.tne lessons I need to learn before we head off to remote locations.

One more.thing I carry 10Litr jerry can of clean diesel, mostly it's for the webasto but I have made a emergency fuel pipe now, just a bit of hose with a outboard primer pump and filter so i can bypass the whole system and run the engine out of the jerry can in the event of a problem, enough to get me home.

Great to learn all the systems.
I was asked to help a couple prep for a trans Atlantic once. The first day I turned up they were like let's go. I spent the morning going over the boat with them. They had no idea how anything actually worked. You really need to a diesel engine maintenance course, basic electrical, medical and safety course as a minimum. Sailing is the easy part. They never did it. They didn't want to take someone with them and did a couple of overnight trips and decided it wasn't a good idea.
Its amazing how quick a jerrycan runs out!
Without the fuel return!!!
Depending on the engine and state of the injectors a lot of diesel gets returned to the tank. A 20 L Jerry can didn't last long on a 3 cylinder yanmar!!

Good point about the return line, I hadn't thought if that. Hopefully never need to do it, I am going to be a bit fanatical about fuel cleanliness after this episode.

Any fuel bleed through the injector that is not returned to the tank is usually returned to the filter on the LP supply side. I don't understand how a tank of fuel would last longer with a fuel tank return. The more the internal components of the injectors are worn, the more bypass you will have returned to the filter or tank and less fuel will be delivered into the cylinder.
Unless of course you have the bleed just venting straight into the bilge

After It happened to me I did a bit of research and asked some engineers. It seems to vary between engines. i never really got an answer to what % of fuels goes back into the tank. As I said my experience was with a 3 cylinder yanmar. I can actually hear fuel dribbling back into the tank. Its a stainless tank so you can hear it easily. On various forums people said the same, they could hear a constant dribble. On the other hand one guy took the return hose off to measure it and said there was bugger all fuel going back into his tank.
I had to do about 12-13 Nm. The 20 L tank only just made it. Normally we use 2.5-3 L an hour at 5 knots.

Most marine diesels return the fuel direct to the tank. Some diesels in cars return to the filter. Check what your engine has and carry some extra rubber hose to take the fuel back to the jerrycan if needed.

Yes should have added that. Now I carry extra hose as well.

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tarquin1 said..
After It happened to me I did a bit of research and asked some engineers. It seems to vary between engines. i never really got an answer to what % of fuels goes back into the tank. As I said my experience was with a 3 cylinder yanmar. I can actually hear fuel dribbling back into the tank. Its a stainless tank so you can hear it easily. On various forums people said the same, they could hear a constant dribble. On the other hand one guy took the return hose off to measure it and said there was bugger all fuel going back into his tank.
I had to do about 12-13 Nm. The 20 L tank only just made it. Normally we use 2.5-3 L an hour at 5 knots.

Yeah but, it's the engine's injection pump that determines the fuel consumption. With a return to the tank the lift/ or supply pump will always pump to a capacity higher than what is required by the engine simply because it can return to the tank. If you have no return to the tank the lift pump will only supply what is required by the engine because excess fuel has no where to go.
The main advantage of returning fuel to the tank is that it carries air out of the fueling system and it helps control fuel temperature.
Some bleeds return directly to the tank, others return to the filter and have another return line from the filter to tank.
I struggle with the point you are making about the Jerry can lasting longer because of a fuel return.

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Jolene said..

tarquin1 said..
After It happened to me I did a bit of research and asked some engineers. It seems to vary between engines. i never really got an answer to what % of fuels goes back into the tank. As I said my experience was with a 3 cylinder yanmar. I can actually hear fuel dribbling back into the tank. Its a stainless tank so you can hear it easily. On various forums people said the same, they could hear a constant dribble. On the other hand one guy took the return hose off to measure it and said there was bugger all fuel going back into his tank.
I had to do about 12-13 Nm. The 20 L tank only just made it. Normally we use 2.5-3 L an hour at 5 knots.

Yeah but, it's the engine's injection pump that determines the fuel consumption. With a return to the tank the lift/ or supply pump will always pump to a capacity higher than what is required by the engine simply because it can return to the tank. If you have no return to the tank the lift pump will only supply what is required by the engine because excess fuel has no where to go.
The main advantage of returning fuel to the tank is that it carries air out of the fueling system and it helps control fuel temperature.
Some bleeds return directly to the tank, others return to the filter and have another return line from the filter to tank.
I struggle with the point you are making about the Jerry can lasting longer because of a fuel return.

Thanks Joelene,
That was really interesting. I often wondered what happened when there is no return or a blocked return.

If you are suckling 3 L an hour out of a jerry can and the engine uses 2 and 1 goes back into your main tank you are taking 3 L an hour out of the Jerry can. If you put the return hose back into the Jerry can that litre is going back into the Jerry can and you are only using 2 L an hour out of the Jerry can.

Thank you, for explaining it

As I said I was pretty shocked when I saw how much fuel we had used out of the Jerry can. The other thing was when I looked into it how many different answers I got. There dosnt seem be a simple calculation. "Yep fuel return hose" and that's it.
We also added an in line fuel pump as the tank is a long way from the engine. I think this is pushing more fuel through so we have lots going back into the tank. Again it seems to vary hugely between engines and how they are setup.

All the naturally aspirated engines I've owned return fuel in a steady flow, interesting that it's not a specific amount. My Detroit 2stroke pours diesel back into the tanks but that's another world as the injectors are also the high pressure pump

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woko said..
All the naturally aspirated engines I've owned return fuel in a steady flow, interesting that it's not a specific amount. My Detroit 2stroke pours diesel back into the tanks but that's another world as the injectors are also the high pressure pump

There should be a lot. The fuel under pressure gets hot. Hot fuel costs hp. The fuel tank cools the fuel. In my boat the return line to the tank is about 15 feet long. In my race car I have a fuel cooler in the return line.

Yet another good reason to keep the tanks pressed up

Interesting
My yanmar has fuel return to filter. Nothing to tank.

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Ramona said..

woko said..
All the naturally aspirated engines I've owned return fuel in a steady flow, interesting that it's not a specific amount. My Detroit 2stroke pours diesel back into the tanks but that's another world as the injectors are also the high pressure pump

There should be a lot. The fuel under pressure gets hot. Hot fuel costs hp. The fuel tank cools the fuel. In my boat the return line to the tank is about 15 feet long. In my race car I have a fuel cooler in the return line.

Yes this is something else I learnt. Warm fuel is less efficient. So if that is the case a return line to the tank is better than directly to the filter?