Two year old diesel fuel

Dec 22, 2012
102
Islander 30 Bahama Keyport
For a number of reasons, my boat has been on the hard for two seasons with a full tank of diesel fuel. I added stabilizer (Bio-something) back then but hadn't done anything to it since. Will be OK just adding some other additive or do I need to drain the tank? If I do, how do I dispose of the drained fuel?
 

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
22,959
CAL 35 Cruiser #21 moored EVERETT WA
Nestor, How big of a tank are you talking about?

Issue is diesel fuel could have water in the bottom of the tank. There could be algae that has found the water a great place to grow. You will need to inspect the fuel in the tank to know.

What to do is up to you. I bought a boat with unknown age of fuel. We are talking possibly more than 3 years. I found that the fuel caps did not have an o-ring so possible water had entered the fuel. There was over 100 gallons of fuel in the 2 tanks.

My decision, was to take a sample and get it analyzed. Info came back that fuel was ok to burn in my engine.

Options for getting at the critters and water. you can polish the fuel. Run the fuel through a filter and return it to the tank. Do this so that several tanks of fuel have gone through the filter. You should be able to remove most any critters (look like coffee grounds in the filter) and any water that had found it's way in to your fuel. The go ahead and put it to use. You may need to use an additive to boast the fuel. The sample test should give you all the info you need. Likely someone with a diesel heater would be glad to take your fuel should you want to give it away.
 

DougM

.
Jul 24, 2005
2,242
Beneteau 323 Manistee, MI
My boat sat on the hard for two winters with a full tank of fuel. Launched this spring, and it started up and ran fine. I have never used a full tank of fuel (17 gallon tank) in a season. The one time I drained the tank, the fuel was completely clear. The guys in the yard took the fuel to burn in a diesel heater used to heat their work area in winter.
I just change the primary fuel filter annually, and it never seems to pick up any crud. Probably, lucky on my part, but living in a colder climate may also be a factor in not developing much junk in the fuel as well a getting fuel from a marina that dispenses a lot of fuel over the course of a boating season.
 
Jul 7, 2004
8,481
Hunter 30T Cheney, KS
My diesel is about 2 years old. I put Startron Enzyme fuel treatment and Hammonds Biobor JF diesel fuel treatment in when I filled it. It started fine after the winter sleep

I think you have to do it up front. I don't know if adding it after 2 seasons would do anything
 
Jan 27, 2008
3,086
ODay 35 Beaufort, NC
Does your tank have any way to get in there to clean it like a cover screwed on the top of the tank? A lot of places have emergency generators that rarely or never get used and the fuel sits for years sometimes. So the fuel is pretty robust for longevity. If the fuel is known to be contaminated you should drain and clean the tank, if not it will likely work fine. If you have an electric fuel pump on the boat, put the output hose in a mason jar or Ziploc bag and pump a small sample. Or take off the fuel gage from the tank and siphon out a sample from the bottom of the tank into a jar or clear bag. Look at the fuel, if it is cloudy or looks like slimey stuff in it, it is contaminated. If perfectly clear it should be fine. If it is bad, get some 5 gallon tanks and pump the fuel into them to drain the tank. Or get a polishing service to clean the tank for you and clean the fuel. You can make a simple polishing rig with an electric pump and a filter and pump the fuel through the filter while it is coming out of the tank into the jugs. Then have one empty clean 5 gallon jug. Pump the fuel from the jugs into the clean tank. You will now have fuel cleaned and water separated twice in the clean jug. Pump it into the empty boat tank and it will be the third time it is filtered. Do this with the rest of the fuel and the fuel should be pretty clean. Now when the engine pulls the fuel from the tank it will be filtered and water separated in your primary filter again (4th filtration) and then through the engine filter (5th time) before it hits your injectors. You can also give the fuel to a diesel boat that uses a lot of fuel every day like a charter boat or a fishing boat, they will likely be happy to get some free fuel. Auto stores sell electric diesel pumps pretty inexpensive, and you can get a low cost filter at a tractor supply store for a home polishing rig.
 

Gunni

.
Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
A plastic tube can be lowered to the tank bottom, then plug the top of the tube with your thumb and withdraw - you get a profile of the tank contents. If water extract with a siphon or pump with bottom pickup. You want to get any algae layer too. I have seen emergency generator fuel last years in proper storage. If in doubt you can have the fuel tested and adjust the cetane
 
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SG

.
Feb 11, 2017
1,670
J/Boat J/160 Annapolis
Beyond the comments above: Do you have an access port on the top of the tank? If so, I'd get in there and visually inspect the tank. You can get growth on the bottom and sides which additives don't touch and which will encourage additional growth. If you don't have a problem, there's piece of minds. If you do, then that's the only way to clean it.

You' can also see whether there is water which, in addition to encouraging growth, can accelerate deterioration of the tank.

Assuming you have primary and secondary filters for particulate and water reparations, I think that you should be good to go. Watch the filters vigilantly for the next 10 hours, or so. (I'd take a photo of the filter bowl and filter, if you have a Racor that will allow you do so. You can then compare what's happening.)

Your Islander shouldn't have a turbo charged engine; and, I think that a simple, aspirated diesel engine that is operated within "reasonable" rpm and load ranges is more tolerant of fuel quality than a high performance engine that you're "pushing". Having said that, running an engine that is warmed-up, with clean oil at higher RPMs is good for it.

Also -- MAKE SURE YOU CHANGE THE OIL and filters before you go out for a variety of reasons. I'd plan on checking that a bunch during the first 20 hours of rerunning the engine.
 
Sep 23, 2009
1,475
O'Day 34-At Last Rock Hall, Md
In a constant warm climate maybe you might have some growth and Jibes and Gunni have given you good advice. However I would not worry about it. My boat sat for over 2 years, not sure the elmer po put any additives in, and it started right up. I monitored the Racor filter that I had installed for signs of water or debris and never found any.
 
Jul 7, 2004
8,481
Hunter 30T Cheney, KS
I forgot to mention that I have and H2Out vent filter. Had to rejuvenate the desiccant before I put her in the water this year.
My ramblings are more about prevention that inspection. May be of some use to someone reading this thread.
I prefer my older style glass canister because I can see the desiccant. I guess they break if you aren't careful.

 
Jan 24, 2009
450
1981 Cherubini Hunter 27 Shipwright Harbor Marina, MD
I am in the process of replacing my fuel tank and used these to empty the tank of the "years" old fuel:
Super Siphon to get the bulk of it out: https://www.amazon.com/gp/product/B01JSG7FK4/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1
A battery powered gas transfer pump: https://www.amazon.com/Sierra-Tools...d=1496929422&sr=1-1&keywords=battery+gas+pump
(This pump requires some headroom and I had to pull the tank out to use it)
I gave about 8 gallons of relatively clear fuel to the guy helping me and he poured it into his trawler through this filter funnel I got at West Marine: https://www.westmarine.com/buy/flo-...ve-portable-fuel-filter--16923591?recordNum=2. This funnel lets the water separate out while you are pouring fuel through it. The couple of pints of really gunky fuel was poured into a 5 gal can that has old waste oil in it for recycling.
==> There is a service that will come and polish or pump out and haul away fuel, which is probably the best/easiest option, but also the most expensive.
 
May 24, 2004
7,164
CC 30 South Florida
Disconnect the fuel line either at the petcock from the tank or at the water separator and let some flow into a container by gravity. Check to see if it is clear, if it smells like diesel fuel and rub some between your thumb and forefinger to see if it is oily. Chances are if it passes these inspections that it should burn adequately. Now I cannot speak for the bottom of the tank where condensation may have settled and the carcasses of bacteria may be forming a crust. I would replace filters and fire the engine up and see how she starts and runs. She might run well when on an even keel but be aware that if you hit some rough seas all the crap in the bottom of the tank may become dislodged and clog your water separator filter. Have spare filters on hand. If you have any recurring problems with clogged filters then you may need to drain any remaining fuel and water, install an inspection port and clean the tank before refilling.
 
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