View Full Version : Fuel Tanks and Dirt and Stuff

11-05-2002, 07:26 PM
We've appreciated the questions and answers regarding engines in the forum. There is a lot of experience here in the forum.
We have 2 diesel fuel tanks 15 gallons each.We launched the boat in August. {She was out of the water about 3 years}. There was still fuel in the tanks and there is black gunk too! This black gunk plugged the fuel pump on our last sail of the year. The black gunk is now plugging both fuel lines. Any advice on cleaning the tanks in place?
We can't get the tanks out without destroying the cockpit.
Any help would be greatly appreciated.

Peter Malcolm Jardine
11-05-2002, 07:52 PM
Diesel fuel will actually grow a fungus when it is left in tanks for a while... the only thing you can do is to flush them.. repeatedly.. and then install a very good fuel filter. Ray... something I can't remember the brand name. Help? anyway.. you should have a good fuel filter set up if you are in larger waters, simply because the chance of getting bad diesel is always there. There is also fuel additives for storage purposes that should be used if you don't go through a lot of fuel in a season

Peter Malcolm Jardine
11-05-2002, 07:57 PM
Oh, and there is a possibility of drilling a hole in the tank to drain it if there is no drain. then tap the hole and insert a spigot or drain plug afterwards. Can you use a pump to pump the tanks? The fuel lines and so on will have to be removed and completely cleaned. Injector cleaner might help you if the engine has been contaminated.
Hope this helps

Phil Young
11-05-2002, 10:07 PM
And there are companies who come to you, put a tube or two down the filler hole and "polish" the fuel-involves repeatedly passing through a big filter. Probably not cost practicable for 2 small tanks though. I'd suggest you pump some compressed air or something backwards through the fuel lines to unplug them, get the fuel well stirred up by blowing bubbles nto it, suck it all out, do that again with clean fuel, throw all the fuel away and put some more clean stuff in. Then change your fuel filter after a short run, and again as soon as you go through some lumpy water.

11-06-2002, 05:54 AM
Nasty stuff - I found about a gallon of this black mud in the bottom of each of Grantala's tanks when I cut them out. The mud was the dead bacteria that grow on the fuel / water interface when you get moisture in your tanks - which is more likely if you leave the tanks half empty.

Have fun!


Scott Rosen
11-06-2002, 06:18 AM
There's a product called BioBor, or something like that, which kills any organisms that might be living in your fuel tank. You can give it an intital "shock treatment" and then follow up with regular treatments. I add some during spring commissioning and in the fall.

The stuff really works. You should make it part of your normal maintanence.

11-06-2002, 08:12 AM
Rosebud, Are you sure the fuel pump is clogged?

I looked at my old engine and there are two filters in the line from the tank: One large one and another, finer filter, in the body of the fuel pump. My new engine has three: One large one in the fuel line, the next mounted on the engine, and a third in the body of the fuel pump. That's a lot of filtering and I'm guessing the filters would get clogged long before the gunk would reach the fuel pump,..or...Heaven help you...the injector pump, itself.

I'd find a compressed air source and blow everything back from the point where the fuel enters the fuel pump, replace every filter and hope that when you have the gunk out of the tanks and the fuel lines, you've solved the problem.

When I read your post I started to worry that the engine, not being run for three years, may have formed some other gunk further down the line, in the water separator/filter, the lines or the secondary filter.

If you have the winter to get these things sorted out, I'd remove the injectors and have them checked out, cleaned and tested. Injectors have filters, too.

11-06-2002, 07:43 PM
Thanks for all the good advice. Actually , as RodCross said, the fuel/water separator was pretty bad. We cleaned that first before we tracked down the fuel pump clog. We'll try the compressed air - we have a couple of scuba tanks needing inspection.

Thanks again

Rose and Bud