3 Year Old Diesel Fuel

Bought a boat with 1000+ gallons of diesel fuel in fiberglass intregal tanks (900 gal and 400 gal) that is 3 years old. The boats only use has been an occasional engine start and run over the 3 years. The twin Yanmar 75hp engines ran fine during the sea trial and have had a complete engine service (all fluids and filters impeller etc.) The certified and respected Yanmar mechanic that did the engine service said to treat he fuel with FFP Plus 8 to raise the cetane level and just polish the fuel and burn it. The boat has a Racor fuel polisher and duel filters system for both engine and Genset. Anyone have any other words of wisdom to consider?

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Change the polishing filter before you polish the fuel, if you haven't already. Also I would put some Star Tron in the tanks.

Since we have not used our boat too much in the last 2 years, some of the fuel must be 3 years old (900 gallon tanks). Ran just fine this past Summer. We do have fuel polishing but apparently not needed. I think the key to "old" diesel is how much water is in it.

They sure put sharp bends in those cables - interesting to see what kind of voltage drop you have.

All diesel has "some" water in it, it is introduced right from the refinery. The difficulty is biological growth, which can bung up everything. Sounds like you have already gotten good advice.

N4712 said:

Change the polishing filter before you polish the fuel, if you haven't already. Also I would put some Star Tron in the tanks.

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Wouldn't you want to wait to change the polisher filter until there is an indication that the filter is full?

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Spottsville said:

Wouldn't you want to wait to change the polisher filter until there is an indication that the filter is full? Sent from my iPad using Trawler

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Well sitting for 3 years , I'm sure it could use a change.

Where is the fuel polishing system picking up the fuel from, the bottom of the tanks, or through a top draw that ends below the bottom.

There may be crud on the bottom of the tanks. If the fuel polishing supply is the same as the engine then the suction will not lift any crud off the bottom.

Marty

If you are planning an extended offshore passage it might be worth having the tanks and the fuel cleaned professionally before you leave. Otherwise, just polish it onboard and use it. Keep a supply of polishing filters and Racors on board just in case. As previous, I know that I have used 3 year old diesel with no hint of a problem.

Yup. . .Make sure there is no water or growth and use it. It will burn just fine.

use only one additive...something with a cetane booster would be good...

with that amount of fuel...before I wasted my time doing anything...I'd probably send a sample or two or three out for testing to see what I've got to start with and go from there

Water in the fuel , and perhaps bug bodies would be the only hassle , and most filters will take care of both.

Cetane improver wont hurt , but may not make a noticible difference .

I would keep plenty of filters on hand. I don't think you will have much problem with the tanks full but as you run the fuel levels down you will expose more of the tank to sloshing fuel that may knock down some crud that will find its way to the tank pick-ups.

I don't recall if Ken puts clean outs in the tanks. If he does run the levels down to where you can transfer all the fuel to one or the other and clean them out one at a time. If the first one is OK then you are done. If not run out of the clean one and transfer from the other to it using your polishing system then clean it out too when it is empty.

Also your engines will run better as you add fresh fuel. Congratulations on your new to you boat. I am sure you will figure out who I am

Our boat had 7 year old fuel in her when we bought her. We had it polished, added lubricants raised cetane bought some extra filters than headed north for 1000 miles. Had to change the filters once. The engines ran perfect and that was 1300 hours ago.

Daddyo said:

Our boat had 7 year old fuel in her when we bought her. ...The engines ran perfect and that was 1300 hours ago.

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That is probably the most common and most likely outcome. I wouldn't have bothered with the lubricant but the cetane booster wasn't a bad idea, certainly didn't hurt anything.

There is much ado about nothing when it comes to fuel and the majority of "problems" can be dealt with by normal filtration.

We bought our Marine Trader trawler 1-1/2 years ago. Our boat had an almost full fuel tank and had sat dormant for a year and lightly used for years before that. We had the fuel polished before we left the Keys for Cape Coral. There was so much gunk in the tank, it broke the contractors pump. The octane level was low so we added an additive, and we were only able to top off the tanks with 25 gallons of fresh fuel in each tank before our trip home.

Our trip took us out in the Gulf of Mexico. The first day the boat ran great. We anchored off Everglades City. The next morning of our 2 day trip home, the engines wouldn't start. Raycor filters completely clogged after one day's use (about 10 hrs). Changed the Raycors, and headed home for the last leg of our trip home. Boat ran great. After we got home, filters clogged.

This went on till we ran the boat for several months, replenishing the fuel frequently. I guess given the price of diesel, we did ok just having to replace filters.

Gina

Xsbank said:

They sure put sharp bends in those cables - interesting to see what kind of voltage drop you have.

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Bending an electrical cable will not increase resistance or voltage drop.

WesK said:

Bending an electrical cable will not increase resistance or voltage drop.

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Yep. Bending only is effective on fluid. Brunelli figured that all out years ago. Voltage drop is on length and size of the cable. A little on the connections. I have seen corrosion wick 3 or 4 feet up a wire.

SD

I guess I should have been clearer - the bends are so severe I was postulating some damage. When I get to the boat tomorrow, I will do some bending like that on an old cable and see how robust it is.

Wicking corrosion - there is a fault on some Mercedes where the transmission oil wicks down the electrical cables, where it damages the transmission's brain for a huge repair bill. Another reason to use waterproof connections, not just to protect from water.

Greetings,
Mr. X. No problem with the severe bends. Simply mark an arrow on the wire so the electrons know which way to go.
EG: