Clean diesel tank with no access hatch (or easy access)

[Trundlebug]

I had a similar problem to the OP, in that I couldn't get good enough access to make a hatch.
But I did have enough room to drill a 10mm hole in the top of the tank, in the middle either side of the central vertical baffle.
This enabled me to poke a length of copper pipe (fuel pipe, but central heating microbore will do equally well) down the the bottom of the tank and reach into all the corners.
See my post here http://www.ybw.com/forums/showthread.php?314108-Fuel-Polishing&highlight=fuel+polishing

A couple of points to make regarding some of the replies above.

It isn't sufficient to just filter out the solid black bits and think the fuel is polished; it isn't.
So using a standard CAV type filter isn't sufficient.
You need to use a filter like a Fleetguard that also absorbs water, including dissolved water from the fuel.

This is what actually prevents the bug from returning, as it has nowhere to live.
Decanting fuel, allowing it to settle and returning to tank will not remove the dissolved water which is the root cause of the problem.

Do it properly. Buy a small electric fuel pump, a filter head and a suitable filter (Racor if you must, but Fleetguard is better and also cheaper) and polish the fuel yourself. The right kind of filter will remove up to 95-99% of moisture content. A standard CAV won't, neither will leaving it to settle in a moisture laden fuel can.
It will cost less than getting someone out to do it for you, and you can then do it any time in the future at no extra cost than the replacement filters.

Cleaning the inside of the tank is a nice to have but not as essential as some would have you believe.
I wasn't able to do it and haven't found it necessary.
As there's nowhere for the bug to live, I don't have any bug; I haven't changed my primary fuel filter for over 2 seasons use now, that's around 200 hours.

 

[MagicalArmchair]

I had a similar problem to the OP, in that I couldn't get good enough access to make a hatch.
But I did have enough room to drill a 10mm hole in the top of the tank, in the middle either side of the central vertical baffle.
This enabled me to poke a length of copper pipe (fuel pipe, but central heating microbore will do equally well) down the the bottom of the tank and reach into all the corners.
See my post here http://www.ybw.com/forums/showthread.php?314108-Fuel-Polishing&highlight=fuel+polishing

A couple of points to make regarding some of the replies above.

It isn't sufficient to just filter out the solid black bits and think the fuel is polished; it isn't.
So using a standard CAV type filter isn't sufficient.
You need to use a filter like a Fleetguard that also absorbs water, including dissolved water from the fuel.

This is what actually prevents the bug from returning, as it has nowhere to live.
Decanting fuel, allowing it to settle and returning to tank will not remove the dissolved water which is the root cause of the problem.

Do it properly. Buy a small electric fuel pump, a filter head and a suitable filter (Racor if you must, but Fleetguard is better and also cheaper) and polish the fuel yourself. The right kind of filter will remove up to 95-99% of moisture content. A standard CAV won't, neither will leaving it to settle in a moisture laden fuel can.
It will cost less than getting someone out to do it for you, and you can then do it any time in the future at no extra cost than the replacement filters.

Cleaning the inside of the tank is a nice to have but not as essential as some would have you believe.
I wasn't able to do it and haven't found it necessary.
As there's nowhere for the bug to live, I don't have any bug; I haven't changed my primary fuel filter for over 2 seasons use now, that's around 200 hours.

What do you make of the funnel type filter that promises to separate the water out? I used one of these when Pelaing my fuel out...

 

[lw395]

Interesting paper:
http://www.webpages.uidaho.edu/~bhe/pdfs/MC.pdf

Diesel with bio content can dissolve up to about 1,800ppm at 35degC, but much less at 5 degC, so it can precipitate out at low temps.
So keep the fuel cool when polishing.

IMHO, small quantities of water in diesel or petrol are a fact of life.
Keyword is 'small'.

I don't think the bugs live in the dissolved water, they live in the separated water, and feed off the diesel at the boundary?

 

[Trundlebug]

The water absorbing funnel filters are OK and they do what they say, but seem an expensive way of doing things to me.
I guess if you fill up via jerry cans it's worth a go, but I fill straight from the pump and polish my fuel about once every couple of years. That has seemed quite sufficient since my initial problem when I polished the fuel in my tanks initially. A replacement Fleetguard filter costs me around £20 from memory, and it absorbs loads of sludge and moisture before it's spent. Several times its own weight I'm led to understand.

As the problem is so well under control now, the filter lasts about 2-4 years. Not sure how much those filter funnels cost? But I'm sure they won't absorb anything like as much as a multi-pleated spin on filter.

 

[superheat6k]

I routinely polish my fuel and have dedicated access fittings for this purpose. My rig is a Holley 12v fuel pump with a Baldwin separator filter.




It is more effective to draw the fuel through the filter using the pump suction because the pump's action breaks down particles into much smaller pieces that can then pass through the filter, especially water.

I would part fill the tank a few times drawing each time into a clean receiving drum, then pour it back in. Once the majority of the loose muck os out then 3/4 fill the tank and obtain about 7 or 8 clean 20 litre containers.

Then as others have suggested thoroughly agitate, and I would use a rubber open ended hose onto an air compressor, and let it fizz away, and waggle the hose around the tank as much as you can, then suck the entire content through the filter, repeat until no noticeable muck comes out.

Maplins offer simple endoscopes that can be used to see how much muck remains.

Once filtered the fuel is fine to re-use. However, you can filter it several times between drums before putting it back in your tank. Once clean a strong one of dose of Fuelset or similar should kill any remaining bugs, then keep the fuel dry, and identify how the water got in - the deck cap seal is the commonest culprit.

 

[LadyInBed]

What happened to the bug killer additives that magically convert bugged fuel to clean fuel?
As advocated on the forum by a chap from the CI's some years back.

 

[westhinder]

Thanks all. I am aware of Ian Nicolson's writings - interesting stuff. However, I still baulk at the option of cutting a hole in the cockpit sole. I will persevere with the methods covered in this thread.

Alisdair, does your tank have a drain plug? The tank in my Rival 34 had one in the forward facing side, at the lowest point of the shallow V formed by the bottom of the tank. If you can draw the fuel off there, it would remove at least a good part of the gunk. If there is no drain plug, it might be worthwhile to put one in.
Anyway, commiserations, the tank in the Rival is the worst place you could wish for to work on. Short of removing the engine or cutting a hole in the cockpit sole it is inaccessible.

 

[lw395]

Alisdair, does your tank have a drain plug? The tank in my Rival 34 had one in the forward facing side, at the lowest point of the shallow V formed by the bottom of the tank. If you can draw the fuel off there, it would remove at least a good part of the gunk. If there is no drain plug, it might be worthwhile to put one in.
Anyway, commiserations, the tank in the Rival is the worst place you could wish for to work on. Short of removing the engine or cutting a hole in the cockpit sole it is inaccessible.

A drain plug is very little help, when you find you have a fair amount of diesel and enough water to worry about in the tank.
A standpipe from the top or side of the tank, going to the lowest point will enable you to remove water at any time without risk of spillage.