Diesel Fuel Question

[Allan12498]

I had to towed back to my slip on the last two outings(thank God for unlimited towing with BOAT/US). After the first event, I wrote it off as the fuel filters needed replacement. When it happened again, I asked for help and it was determined I have fuel contaminated with algea so I faced with fuel disposal, tank cleaning, fuel lines, filters for main and generator etc.

I've got a 50 gal. tank, and when I filled up last October, I had used 7 gallons for my year's usage. I'm showing 3/4 full on my guage. I have had the boat for three years, and I estimate the total fuel I've put in the tank to be 25 gallons which means there was 25 gallons of fuel over three years old in the tank.

My question is with as little fuel usage I have, should I not completely fill the tank? What about additives when fueling, and how long will diesel remain fresh?

 

[RichH]

Fuel oil exposed to atmosphere (vent is connected to atmosphere) only has a 'shelf life' of 'months'.
Several strategies to prevent the infection, chiefly by resin forming funguses:

1. Start with a fully cleaned tank and distribution system.
2. ensure that the deck fill is water tight.
3. Keep only the amount of fuel in the tank that you can reasonably expect to use, plus some reserve.
4. If possible, empty the tank for long term storage.
5. Use a bio-cide to keep the fungals under control and the spores inactivated
5a. "Startron" is a typical appropriate fungicide'
or
5b. Install an onboard recirculation filter ... one that continually filters the fuel over and over and over again.
6. If your tank is of strong construction, close the vent valve when leaving the boat to prevent water vapor and fungal, etc. spore uptake through the vent.

The problem is not 'algae' but funguses that are 'resin formers'. Do websearch for claudosporium resinae, kerosene fungus, etc.

 

[Eddie7045]

KFish, if you're fuel is that bad

you should se about a fuel polishing service to clean your fuel tank. After that use a diesel biocide additive to your fuel at each fillup and keep the fuel level topped off to reduce water condensation in your fuel tank.

 

[Don S/V ILLusion]

Diesel does age although at what rate is a matter of conjecture; more quickly when contaminated by water which is the biggest cause of growth and therefore fuel contamination. Check out the BP Petroleum site at which you will find info from the experts citing the effect of aging (on non-water contaminated) diesel and how futile it is to try to prevent it.

Additives can help slow growth but not in your case as it is already too late. In your climate, it is not as crucial to fill the tank for winter storage to preclude condensation and with your fuel usage, even more reason to not keep it full.

Sound like a thorough tank wall cleaning is in your future. Fuel polishing does just what it's name implies, clean the fuel. The problem is the stuff sloughing off the bottom and walls which will continue to contribute unwanted material into the cleaned fuel until it too is eliminated.

 

[MrBee]

If that's all the fuel you use in a season can you empty you tank, have it cleaned really well then leave it empty. Leave in the boat as designed but install a small tank of 10 to 15 gallons. New tank...Smaller size more friendly to the amount of fuel you use, less likely to contaminate in the future.
Just some thing to think about..

Brian

 

[sailaway78]

Mr. Bee hit it

I think that in your case, Mr.Bee hit the nail right on the head. With that large of a tank, and that little bit of fuel usage, you could have a continuing problem. I think I would empty the tank completely, and get it cleaned. Then just get a smaller tank. One of the six gallon outboard tanks would work. They are cheap, and easy to come by. Instead of having 50 gallons of fuel to worry about, only have six, or maybe even three. For the amount of fuel your talking about using, a six gallon tank would last you nearly a season.

 

[Ross]

Re: Mr. Bee hit it

I installed a ten gallon tank when I rebuilt my boat and always carried a five gallon jerry can as back up. However I find that even that is never "needed". After a long trip with much motoring I top up the tank and refill the jerry can.

 

[Steve Dion]

Don't waste money on fuel polishing. Drain your tank, clean it out and refill with clean fuel. Someone with an oil burner could use this fuel if it is filtered. Otherwise you can just take it to your local fire department for disposal. Many of them use it for their practice sessions.

Fuel polishing can run several hundred dollars.

If you want to be frugal, you can filter your own fuel with a large Baja Filter from WM.

I suggest that you add a biocide to your fuel too.

I am in the process of adding a filter bypass system. This will allow me to run through one of my two filters if I should ever experience a similar. I had a simlar experience a year or so ago and never want to be worried about this type of situation again.

 

[Don12364]

Diesel Bug

All agree you have 'Diesel Bug'. It comes in several forms (and colors, black, brown and the consistency of soft butter when clogging filters and fuel lines).
My experience from two instances when I was caught out is that it only takes 3 days for the bug to grow in the tank to the extent where it clogs everything and stops the engine. i.e. 3 days after the last fill up.
To me this means the last fuel you put in was probably the culprit and was contaminated with plenty of water - for which you no doubt paid in full!

The arguments about condensation in tanks do have relevance but the amount of water taken in this way is not normally enough to reach the pickup tube in the tank. Pickup tubes are deliberately set an inch or more above the tank bottom to avoid picking up too much debris. The bug lives and thrives at the water/fuel interface, though this can get stirred up if you sail in some rough water.
Now I always add 'Fuel Set' to my tank at every refill and have been trouble free this last 8 years.

Though diesel fuel does undoubtedly degrade over time, I have never found this to be a cause of stopping the engine once you have got it running.
By 'time' I mean I have used diesel that is 5 years old with no problems.

 

[zeehag]

remove your fuel
filter it --even coffee filters are good for that
use biocide in your tanks and jerry jugs
diesel is use-able for many years--use a water separator to remove the water that normally gets into the fuel
use a series of filters for your fuel--larger to smaller in series--use the water separator in the primary filter

my diesel fuel is over 5 yrs old and is still good----in 2 boats-----do not buy contaminated fuel--if there is any question about the quality of the fuel, filter it when it goes into your tanks-- and when your tank is low, empty into jugs and clean your tank manually. then filter the fuel remaining into the tank and add biocide.
gasoline has a shelf life that is short--kerosene and diesel have a lot longer time for use, but it needs to be filtered and kept free of algae and crud. good liuck.~~~~~_/)~~~~~