Cleaning a Diesel Tank

[Captain Larry-DH]

Here is an idea.

keenanfilters

keenanfilters

keenanfilters.com

Here is a product that may be helpful.

https://www.fuelright.com/

This interested me, so I started looking online to seek out reviews.
This PS review from 2013 was noteworthy. The only other reviews I found were anecdotal from users, (edit: most were favorable).

“Fuel Right
This product, one of the most expensive in our comparison, was not tested in our previous biocide trial. It is not a registered biocide, although the company claims protection against biological growth.

While the product has its supporters, it was the only product tested that made corrosion worse than the control, and it was the only product that induced pitting in the aluminum sample. Perhaps an increased dose would have helped-it had by far the lowest usage rate-but the product literature did not suggest higher rates for special purposes. Available in 16-ounce, 32-ounce, and 1-gallon bottles, this product is a good example of why boaters need to be wary about manufacturers claims. Bottom line: Not recommended.”

Reference Diesel Additives - Practical Sailor

 

[jibes138]

Would Dawn soap work to remove the scum? Seems like a go to detergent for oil spill cleanups as well as greasy cookware.
I’ve used it to remove old wax from my hull and it dissolves the wax instantly. I’m not suggesting straight Dawn but in a hot water solution.
it is also good for killing fire ant colonies.

 

[chp]

I had the same issue when I got my boat. Previous owner never added any biocide. Complained that once in a while the engine would quit due to fuel starvation. I opened up the tank at the fuel tank level sending unit and the bottom was caked in thick black sludge that was plugging the intake pipe. I built a polisher and ran it for a couple of days stirring up the bottom. Had to empty the separator and change the filter a couple of times there was so much. Same as you I was concerned about the crap on the walls. I found this product and my tank is clean now walls and all. Haven't had any problems in years.

 

[thinwater]

Would Dawn soap work to remove the scum? Seems like a go to detergent for oil spill cleanups as well as greasy cookware.
I’ve used it to remove old wax from my hull and it dissolves the wax instantly. I’m not suggesting straight Dawn but in a hot water solution.
it is also good for killing fire ant colonies.

Actually, the only retail degreaser used by commercial tank cleaners is Simple Green with hot water. Yes, it would probably help.

But for cutting the sludge with a brush, the best degreaser is probably diesel. Commercial cleaners often leave an inch in the tank to clean the sides and bottom, before pumping it dry and finishing up. Common practice.

 

[Cap'n Deke]

No getting around this is an unpleasant chore. It sounds like you have a pretty good grasp on what's involved. There's no right or wrong way to do this, so long as you clean up your mess when you're done. No point in doing all that cleaning only to leave some gunk or detergent in the bottom. Better to use only diesel and elbow grease to do the cleaning, if you can. That gives you less to remove when you're done. If you're making a fuel polisher, you can just use that.

The estimate that this will cost $1200-$2000 to build is several times too high, assuming we are talking about USD. You can make a really good one for a few hundred USD, and a good-enough one for under $200. It's just a fuel pump, a filter or two, some fuel line, and a few fittings. Provided the only contaminants you are worried about are water and particulates, then there is no need to get any fancier. Your tank is only 45 gallons, so you don't need to up-spec this like you might want to handle a bigger tank.

Since your tank is bigger than you need right now, you might want to spend a few minutes making your polisher a bit nicer since it wouldn't be unwise to polish your fuel each spring.

A mate of mine was waiting out the season near my boat in Nuku Hiva. His situation was similar. Since he had several months on his hands, he made a fuel polisher by modifying his fuel pump and filter to recirculate back into the tank. He added biocide and went through several cycles in which he would run the pump for a day while periodically agitating the fuel with an egg whisk on a stick. Then he'd let it rest several days and let the biocide work some more. It worked surprisingly well and he never had to empty the tank. I never saw the tank before he started this, but it looked pretty good a couple of months into it. Don't ask me what treatment he used.

 

[Foswick]

Thanks Deke. I am just waiting on a couple of small parts to put together my fuel polisher. It's laid out in pieces on the floor, right now. I haven't been keeping track but I think it's come in at about $200 with a carrying case (that might end up being too small). I forgot to budget for a whisk, though.

My setup has a 100 micron prefilter, a 300 lph pump, a 10 micron filter/separator, and the plumbing/wiring to put it all together. I'm betting the pump does, on average, moves fuel at about half that rate. So, probably something like an hour to cycle the whole tank. Lacking any hard science, I just figure I'll keep running it until it's run for an hour without visible contaminants in the filter or separator.

I have kind of wondered how effective it would be to do something like what your friend did - treat, then agitate and polish periodically over some time. The only reason I don't try that is because, when the tank is full, I can't confidently pull sediment/water from the bottom of the tank because I can't see it very well. So, I feel like I would risk causing the very problem I was trying to prevent.