The fuel doesn't go bad.. it's the stuff that grows in it and the water that sits in the bottom,that makes it bad You should be able to use the fuel if you really do filter it. not just strain it. I'd suggest you get an access plate for your tank..because the fuel itself is not able to really loosen the crud. or just replace the tank. They are not that expensive and you may already have pin holes in the bottom.

 

Chris,

BE DAMN CAREFUL! I agree with Denise. There are services however that will "polish" fuel.....membranous filtration to restore it to usefulness.

Empty fuel tanks, even diesel, and extremely dangerous when polishing or refurbishing. Ask anyone who's been around, and they can recount horror stories of empty fuel tanks exploding. We just had a man die here in western Pa from a bulldozer tank exploding while he was grinding a fitting off.

 

Chris,

BE DAMN CAREFUL! I agree with Denise. There are services however that will "polish" fuel.....membranous filtration to restore it to usefulness.

Empty fuel tanks, even diesel, and extremely dangerous when polishing or refurbishing. Ask anyone who's been around, and they can recount horror stories of empty fuel tanks exploding. We just had a man die here in western Pa from a bulldozer tank exploding while he was grinding a fitting off.

I was pretty careful. I was in an open and well ventilated area (garage door open on a windy day). The fuel was all in jerry cans when pumped out, and I used funnels when pouring to control spillage.

I knew my tank wasn't in horrible shape because I could see the bottom. I saw critters suspended in it, but the metal of the tank bottom was clearly visible, so I didn't think the cost of a polishing service was justified. In my case, the boat is gutted, so removing the tank completely was very simple. I don't even have batteries on the boat, so no really chance of an errant spark.

By sloshing the tank I stirred everything up and was able to get it out and strained. When I say sloshing, I mean tipping the tank back and forth worse than any seas I've seen about 50-60 times, then pouring and filtering, then repeating until the stuff coming out is clean.

The baja filter I used is the West Marine model which Practical Sailor rated #1, so it's quite a good cleaning / water separation. During my first two passes the fuel was so contaminated that the filter stopped passing ANYTHING after about 5 seconds. I had to keep clearing the Teflon screens to keep things moving. It was very effective, and looking at the bottom of the tank I can see it's 100% better now than when I started.

 

Since you've gone to all that trouble with cleaning the tank start with fresh fuel. If it's 2 years old in your tank & only 10 gallons I'd say get rid of it. Not worth the forty bucks. Diesel will go bad but it takes _years_. Denise is right about the main problem being critters that grow in the oil.

Every fall I drain whats left in my tank and put it in my home heating oil tank. Wipe out the tank in the spring and start fresh.

 

And It's not my fav perfume... jus in case your wondering )

 

Chris

I hope yours is in better shape than mine was!

The tanks CS used were fairly thin steel. My tank didn't leak but I bet it was close to leaking. I replaced it with a custom stainless tank with a bottom outlet with a valve for draining it if I need to. In the CS27 the tank is strapped right under the cockpit sole so an access port will not help with the tank in place, only after it is removed.

 

Fortunately, our tanks are fairly easy to remove when compared to others! I didn't end up needing an access port. In proper lighting I could see all I needed through the fill hole and the sending unit hole.

My tank didn't look anywhere near as bad as yours, so I'm going to keep it for a few more years. A few spots has some light rust, and a few places have paint worn off where the straps slide, but overall I think the tank is still solid.

I would love to put in a new custom SS tank, but that would mean more time to research the deck fill location, mounting system, etc. I need to get this refit done and save some projects for future years!

 

I would love to put in a new custom SS tank, but that would mean more time to research the deck fill location, mounting system, etc. I need to get this refit done and save some projects for future years!

If you do go for a new tank make it out of aluminum, not stainless. It's cheaper, lighter and just as good with diesel.

 

Not much cheaper - the labor is the same either way. And external corrosion is a larger problem with aluminum.

Chris
I relocated my fill to the starboard side deck as that was the reason the tank was rusty. The cockpit sole fill over the tank had leaked for years before I purchased the boat. With people's weight on the cockpit sole a fill there can have issues.

 

I replaced the original mild steel tank in my 1975 Cal recently (the bottom had basically rusted through) with a polyethylene unit from Vetus.

It will never corrode, and a quick glance through the cockpit locker tells me how much diesel I have.

 

I thought about a plastic tank but because the tank isn't supported underneath I decided on stainless. Originally it was strapped to the underside of the cockpit. My new tank is in the same place but has vertical flanges that are bolted to the wood running fore and aft under the cockpit sole.

 

Diesel is more stable than gasoline, but it is still a blend of many ingredients, some volatile, some unstable. If you prevent biomatter from forming, prevent condensation from getting in, there are still apparently volatiles that have evaporated out, and other chemicals that have decayed and turned into varnish and sludge.

If it runs it runs, but if any fuel has been sitting around for two years without stabilants being added? I think I'd rather take it to the waste oil tank and let it be burned off as heating fuel.

 

Assuming this is DIESEL and NOT GASOLINE.

The advice of discarding it (by putting it into your home oil burner tank, etc.) is a good one. The reason is that most of the contamination in diesel fuel will most likely be a fungus species whose 'spores' can easily pass through a BaJa type filter.
That stated, 'many' successive 'filtrations' through a Baja (or even a 'stack' of large paper drip-coffee filters !!!!) will significantly lessen the 'bio-load' of particles.

What you should consider to do if re-filtration is your choice is to filter and refilter and refilter (many times through the same filter) so that when you put the oil into a clean glass container and hold it up between your eyeball and STRONG light ... you see no HAZE in the fuel. This will insure that the 'distribution' of remaining particles will be 'mostly' below 5µM; the 'naked eye' wont be able to 'see' particles (haze) smaller than 5µM and the fuel by then will be close to 'optically clear'. The reason for the 'target of optically clear' is that such particles typically 'agglomerate' into larger and larger particles (grow in size!) over time and then will if 'alive' simply re-infect the tank. This will allow you to 're-start' with fairly 'clean' and particle free (greater than 5µM removed) fuel.
Q - When is Diesel fuel bad? Answ: - when its not 'optically clear' when you hold it up to STRONG light and you see a HAZE (or worse).

Your "racor" should be a 10µM, not a 2µM... and the small engine mounted 'guard' filter should be 15-17µM. If you get a lot of rust and other 'hard' particles (from your usual fuel supplier or from rust etc. from the tank) then the system should be tank --> 30µM ---> 10µM ---> 15-17µM (guard filter mounted on engine).

Summary: filter and filter and re-filter the fuel until optically clear, then add an enzyme type 'stabilizer' or 'tank cleaner' to the fuel. Thats it, youll be good to go. Plan on cleaning out the tank every year or so.
Note: if you can, wipe your fingers on the inside of the tank ... if your fingers pick up black slime or any 'heavy black', this is a fungus colony and HAS to be cleaned out as cleaning up the oil will be of no benefit until you remove the fungus that is using the oil as its nutrient source. The 'black' is usually a 'mat' of dead cells and resinous by-products of the organisms metabolism --- has to be 'removed' ... or you WILL have 'filter problems' later on.
The 'easiest' way to clean out a small tank is to take it to a 'radiator' or 'heat exchanger' shop and have it 'ultrasonically' cleaned.

Hope this helps. ;-)