Fuel tank gunk

[drh1965]

Originally Posted by S/V Elusive

Darrell - mechanics will do which ever is needed - if a total rebuild, it would have to come out. As for fuel polishing - check around Clear Lake / Kemah for someone who does that. Most chandlers would know of someone. Check for pump out services - they often provide the fuel polishing service too.

Is fuel polishing and tank cleaning the same thing? I thought fuel polishing just cleaned the fuel of suspended debris?

[Alan Wheeler]

About half of the products on the market do exactly that. What I mean by disperse is to break up water into small particles allowing them to pass through the filters and through the fuel system.

Actually, the key ingreadiant is Methanol, or Ethanol. Both are hydroscopic. They don't actually break up the water as such, but due to molecular action, bind with water molecules and thus taking the water through as a different molecular structure than a pure droplet of water would be. This is also the main cause of water being suspended in fuel. As the Alcohols will happily suspend the moisture mix within the fuel its'elf. Oil is hydroscopic. It will not bind with water molecules and thus the water separates out onto tank sides and floor. No extra additive required.
Water gets into fuels because much of the way fuel is handled in bulk storage facilities is to use water to "float" the fuel off the top of the tanks. This is also done in some bulk fuel ships as well. Especially if the fuel being carried is volatile. A fuel tank is at it's most dangerous when it is nearly empty.
Oil by it's very nat

[DaveyJones]

Glad to see we can agree the water's in there anyway.


Most, if not all of the name brand conditioners that allow water to go through the system actually use the exact wording 'disperse water'. While this term may be scientificly incorrect in some university somewhere it has been accepted by most people who buy the stuff like it's going out of style to mean that the water some how goes away.

Emulsify - to break up into small pieces.
Disperse - To distribute (particles) evenly throughout a medium.


I'm really sorry if I exagerated the percentages. I currently only use about 500 gallons a day. On the water just one of our vessels used 50 gallons an hour 24 hours a day. By comparison what I use now is nothing.

If it were 5% this would mean we would have thousands of gallons of water in a short time. Actually it takes a little while for the water to build up to where you have a hundred gallons or so.

The point is we get water in there somehow.

Generally the bottom of the bulk tanks are not to ever be used. If you get down past a couple of hundred gallons your going to have a major problem.


The average sailboat owner may fillup what? Once a year? The fact that they may not have water does not mean they will be as lucky next year.

The boats I have run had a small tank in the engine room. The large tank gravity fed the small tank. The filters were fed fuel from the top of the small tank. The small tank would collect the water and bugs as they settled to the bottom. There was a drain at the bottom of this tank and it had to be drained on a regular basis. I collected all of this and pumped it off to our waste tank every time I came in.

Unfortunatly most boats probably do not have a waste tank available. This is a really bad thing because I'm sure that a lot of boats simply use what's commonly referred to as 'the midnight valve'.

Another reason why I want a sailboat.



Anyway, now my truck has a fuel conditioning module that does a great job and I just have to pull the drain handle once a week and drain the water.

I buy fuel at large truck stops for my truck and have not had a problem.

[Pelagic]

As I said before, professional fuel/tank cleaning may not be an option for your size but if you cannot network a solution for a small job thru them…. then Delmarry’s advice via pressure wash would be best.

The quickest way to get the majority of the gunk out, would be to connect to the supply line FROM the tank to the primary filter and make an extension to a temporary waste collection for the dirty diesel. After repeated flushing ….suck out dry everything remaining on the bottom, below the supply valve.

Try and rent a small centrifuge rated for diesel to treat and reuse your old fuel as a wash, but when finished put in new clean diesel, pull all you filters, mechanically clean out the gunk there and purge out the lines with clean fuel. (If really bad also disconnect the return line and clean out.) Put in new filters and consider a duplex system so that you can change filters underway while engine is still running

As someone else suggested, the best insurance in the future is to always keep your tanks full

[GordMay]

The April May issue of Professional BoatBuilder magazine has an article by Steve D’Antonio about Fuel Polishing:
Goto Issue 112, pages100 thru’ 110:
Professional BoatBuilder - April/May 2008