Old Diesel Fuel, should I be worried?

[duffer1960]

Here is the background/timeline:
The boat is freshwater sailed on Lake Erie, south of Detroit. Due to other projects last summer, it was never launched and stayed sitting on the hard. The previous summer ('06), it was put in the water in mid-June but not used until taken out in October where we proceeded to get stuck in the mud in the middle of the channel due to the water blowing out of the west end of Lake Erie, and had to run the engine pretty hard to get un-stuck (we actually ended up running two anchor lines tied end to end to shore and using one of our clubs tractors to get us out of the muck). The summer before ('05), we went on a two week cruise motoring most of the time. To make a long story short, the fuel in the tank has been in there since summer of '05 without much sloshing around. Do you think this will give me problems, or should I be ok? I plan on getting her in the water by the end of this month. It is a 35 gallon tank, but unfortunately, I don't know how much fuel is in there because my guage doesn't work.

[artbyjody]

Personally - I would ditch all of the remaining fuel and start fresh. You will also probably need to scrub the tank as there most likely will be alot of sludge and algae in there if sitting that long prior to refilling (it would be a good time to replace the sender unit or remove it and clean it as its probably not working due to the build-ups in the tank (maybe)...)

[sailingdog]

Fuel that's been sitting for two years... I'd either pay someone to polish the fuel or pump it out, clean the tank and get fresh...

[hellosailor]

A partly-filled tank will now have biomatter and condensate in it, the only questions are "how much" and the answer really doesn't matter, since "any" is too much.

Fuel polishing services cost you money instead of time. The choices are hiring one, or pulling the tank and cleaning it yourself (takes some time & effort, costs next to nothing) or just topping it up and setting out with spare filters and hoping they can eat up all the crud before you need to call for a tow.

Personally I'd pull the tank and clean it out, that way I know the guy who did the work and can come after him if he doesn't do a good job.[g]

You clean out a fuel tank just like a big stew pot. Remove the sender, remove any access plate, use a toilet bowl brush and scalding water (if you can get it) and detergent to clean it out. Liquid Tide is very good for this.

Then rinse thoroughly. If there's gunk you can't get at, pour in rock salt or coarse koshering salt with just a little cold water and shake/roll the tank around. The salt is a good abrasive to clean out gunk--and comes out completely with a good water wash.

Then set the tank in the sun for 24 hours to dry out. Or use a hair drier, etc. to speed that up. Reinstall and you're in business.

And make a habit of keeping the tank full, and adding in some stabilant pretty much all the time, if there's a chance that fuel will not be burned up during the next weeks/months.

[sailingdog]

HS-

A lot of tanks aren't easily removed, and many don't have inspection/clean out ports.

[hellosailor]

Two men, two hours, a two more to put it back, and a third guy to hold the rudder back up....finesse the steering and battery cables out of the way...

I guess it depends on your definition of "Easy", huh? [g]

[RAGTIMEDON]

My tank would take a lot of time and effort to remove -- since I have had this boat (5 years) I have probably not used 50 gallons - after all, it is a sail boat! If there is no wind, we usually stay at the dock, or just motor out about 2 miles to anchor overnight behind an island. I always put fuel stabilizer in a full tank in the fall. I hope I don't ever have to dump the fuel, clean the tank, and start over because she holds 300 dollars worth at today's price! Before I retire and live on her, I will probably invest in a filter, pump, and tank with which I can "polish" the fuel- there are no fuel polishing services in this area. I'm sure I can get a filter and pump for less than 3 boat bucks! Tank can be a 55 gallon drum which I can get at work, free. Yes, I know I need an explosion proof pump. Probably a furnace pump will work - they are made for #2 fuel oil, which is not much different from diesel. The easiest thing to get is a Racor filter. Anyone have a better suggestion?

[jgaddis]

What do you do with the diesel that's in the tank that is bad when you want to clean the tank?

[Freesail99]

What do you do with the diesel that's in the tank that is bad when you want to clean the tank?

If you heat with oil, it be perfect as a small oil tank is 275 gallons. 20 gallons or so of diesel would burn fine mixed in with the number 2 heaing oil.

[knothead]

Originally Posted by duffer1960

....Do you think this will give me problems, or should I be ok? I plan on getting her in the water by the end of this month. It is a 35 gallon tank, but unfortunately, I don't know how much fuel is in there because my guage doesn't work.

You didn't mention whether or not the diesel presently in the tank contained an additive designed to keep things from growing.
Assuming it didn't, I think it will certainly give you problems.
The question is, what problems.

If the engine starts and runs then the problem will likely be limited to clogged filters.
How much do you like changing filters?

Frankly, before I made a decision in a case like yours I would fire the engine up and rock the crap out of the boat in the slip or at the mooring and try to clog the filters.
If they clog right away then I would probably decide to remove and discard the fuel and then clean the tank.
If, despite my best efforts to shake things up the engine keeps running I would probably buy some extra filters, maybe even go so far as to install an extra, easily accessible inline filter and go for a long motor sail.
If things go well I would fill her up with new fuel and go on my way.