Contaminated Diesel (Algae?) - solutions and prevention

[Kvetched]

As I have had the joy of this exact situation on our Catamaran, I would like to offer the following: We had a fouled tank with the dreaded sludge last year. Due to the baffles within the tank, we could not clean out the tank to eliminate the sludge. The sludge had fouled our fuel lines/pickup; and we were forced to run the engines off jerry cans.

I did some research, and found Starbrite tank cleaner. This chemical was touted as an enzyme that would break-up and remove sludge and varnish. We put the tank cleaner into the tank, and left it to do its best over the next 30 days. I had constructed a fuel polisher in that time, and when i ran the fuel from the tank into Jerry Cans; there was no sludge within the filter(whereas I had fouled the filters on the engines within a short time prior to using the cleaner.

I polished the fuel as I pulled it out of the tank, and then again running it back into the tank. Added Killem Biocide, blew out the lines; and have been prolem free for the last year. Filters are clean on both engines and Generator; no sludge or contaminates appear in the fule bowls, and the engines run well.

I would recommend to give this product a try, as it might just save you from pulling the tank.

[OneBoatman]

It is the case that many Catalinas were commissioned with only a fine mesh bronze screen fitted over the fuel pickup. Unscrew the plate on top of your fuel tank which will allow you to pull the out the sender and down tube and remove that screen. The black algae that grows in diesel (not a true algae) has an affinity for this and will readily clog the fuel pick-up and starve the engine. It will first first exhibit as intermittent starvation (a sudden tendency to stall without warning, the engine just dies) sometimes you may be able to restart when the clogging is washed away by motion in rough seas or after a period of sitting. Most marine mechanics agree that the best most permanent fix is to simply remove this screen so long as you have a fuel water separator properly in line and of course the factory fuel filter on the engine. Also do not use anything less a 20 micron in the fuel water separator, as the one on your engine is typically rated at 10 micron. If there is a lot of growth in the fuel tank at some point you may consider also having the fuel polished. that would be if the filter are loading up rapidly. (also able to starve in the extreme) Continue to use your algaecide. All filters increase in their filtering efficiency in use, at the expense of increase in back pressure. That is brand new they pass only particles smaller than the media rating at, and as they clog with debris, the particles that make it through are even finer. I use a 30 micron in my fuel water separator and the std ~10 micron in the filter on engine. I replace them both every couple hundred hours of run time and in thirty years I have never had a clogged injector.

[sinnerman]

Fuel system needs water to grow the black algae.

Some of the water comes from condensation, however an overlooked item for water ingress is the deck fuel cap.

If the deck filler cap is not sealing correctly it can allow water to enter the tank...

my two cents

cheers

[sinnerman]

If I had a bogger boat, I would have a 120 volt ac generator.

You can charge the batteries. (normal battery charger)

You can run things on the boat which take power (refrig, ac, etc.)

You are not running the main engine in idle out of gear just to charge batteries (Not healthy for a diesel)..

my two cents

cheers

[christian.kautz]

Hi folks, there were a lot of more or less useful hints to solve the problem. To take a seperate tank for the weekend is a good idea if you lead the returnline back to this tank. Otherwise all the returns (and there will be a lot) go the contaminated tank and will be discarded later.
Let me add another one:Get some (more than one) fuelfilters, filtercartridgets ore something else. We used 3 items of 1/2" waterfilters filled with rag. Add them one by one into the line - beginning with the roughest to the finest - between tank and motorfilter (clean the motorfilter first). Run the engine, these filters will soon get stuck. Just clean them out and continue.
Instead of running the engine You might also use a electric fuelpump after (!) the line of filters to pull out the fuel and return it to the tank, a much faster way. We had 700 liters contaminated gasoil and used this way for about 3 hours, changed fiters several times until the oil was clear.

What ever ur problem was it will be found in the filters.

[Noahr]

Originally Posted by boatpoker

As long as you are going as far as removing the tanks may I suggest a modification ...

The common tank has a pickup tube reaching down to 1/2" to 1" from the bottom of the tank. Some of that 1" or so will inevitably be water. Sitting water is not only the main cause of corrosion (or rust) of metal tanks but the interface of water and diesel fuel is the bacterial breeding ground.

We had our tanks built with bottom fuel feeds. No water ever sits in the bottom of our tanks, it goes immediately to the Racors where it is clearly visible and drained whenever we see it.

I believe a bottom pick-up tube is not possible on a C34 as the tank sit flat on a molded liner platform.

[colinalleck]

Yes I experienced this with my current boat when cruising Great Barrier Reef, for 3 years the filter change showed no problems. One night we were “shaken but not stirred” and sailed into port with jerry container direct feed to lift pump so we could use engine if needed. Be aware diesel fuel return from engine goes to main thank so 20L - 4 gal approx doesn’t last as long as usual.

My best advise drain tank, remove from vessel, if you don’t have inspection port get 1 or 2 installed depending on tank size. Thence thoroughly jet wash tank.

It’s a good opportunity to check tank for potential areas of corrosion that may be areas of failure.

If you want peace when sailing prepare for war and do the most thorough job you can do also replace fuel lines and hose clamps to and from filter and tank.

Then follow the others advise regarding treatments, but try to keep tank full, ]less opportunity for condensation within the tank

Photo shows the 2 inspection ports installed in diesel tank

[robbjd]

I have the same boat(97-C34Mk2) with the same engine & filter arrangement. The Racor I have is R15S, 2 micron filter. That engine also has two fuel filters downstream of the Racor. One on the lift pump, and the final filter on the engine. Treat the tank and have a Racor or two handy and you should be good.

[SV-Apres]

I also had this issue, my engine stopped and no fuel was getting through the system and to the engine. I do the following:

1. Clear the screen - the screen will be somewhere from the base of the fuel filter to the tank - usually in the pick up tube. I blew back the screen to blow off the debris. If I could, I would have removed the screen.
2. Only use Marine Diesel - it has Biocides in it
3. Add enzyme fuel treatment every fueling and at the end of the season, it breaks down the stuff that was killed by the Biocide above (it is not a biocide itself)- https://amzn.to/3QgPR1h
4. Vacuum the tank - I made a fuel polishing system for less than $100 and use it about every 2 years once clean, the first time run it I vacuumed the bottom for about 4hrs, making sure the flow rate through the polisher was still high. here is a pic: