I purchased a boat this winter, I know the oil/filters were changed during the fall haul out, but currently there is about 3/4 of a tank of diesel in the tank. Someone told me that diesel fuel can go bad through the winter. Should I have the old fuel emptied before I use the engine this spring?
Diesel Fuel through the winter
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I would not drain it
Everyone leaves fuel in over the winter. Ideally you are supposed to fill it up and put some preserative in it. I just purchased a used boat last fall and the boat sat all last summer so the fuel is 1.5 yeas old. The consensus is that this too will be ok. I did find out that the previous owner put the preserative in it. You might try and find this out too. I toyed with the thought of draining but the boat yard said it would cost me $4 to $5 per gallon to get rid of the old stuff. This helped me in my decision too. Today I changed the fuel filter in preperation for launch in about 10 days. Good luck to the both of us.
Everyone leaves fuel in over the winter. Ideally you are supposed to fill it up and put some preserative in it. I just purchased a used boat last fall and the boat sat all last summer so the fuel is 1.5 yeas old. The consensus is that this too will be ok. I did find out that the previous owner put the preserative in it. You might try and find this out too. I toyed with the thought of draining but the boat yard said it would cost me $4 to $5 per gallon to get rid of the old stuff. This helped me in my decision too. Today I changed the fuel filter in preperation for launch in about 10 days. Good luck to the both of us.
Drain it only if you have to
I agree with Pat T. If you have problems starting or running, then deal with it. But, if it starts ok and runs ok, I wouldn't lose any sleep over it. Before putting the boat away it is a good idea to top off the tank and put a stabilizer in it. A topped off tank won't have the propensity to accumulate condensation. The stabilizer will stabilize the fuel and it is a good idea to run the stabilized fuel through the injectors too as this will help sludge from mucking up the system.
I agree with Pat T. If you have problems starting or running, then deal with it. But, if it starts ok and runs ok, I wouldn't lose any sleep over it. Before putting the boat away it is a good idea to top off the tank and put a stabilizer in it. A topped off tank won't have the propensity to accumulate condensation. The stabilizer will stabilize the fuel and it is a good idea to run the stabilized fuel through the injectors too as this will help sludge from mucking up the system.
Filling a Tank to let it age is stupid
A smart boater runs his tank almost dry before putting it away for the winter. Then pumps it dry. In the spring you add fresh fuel. This notion that fuel that has stabilizers and has aged over the winter is better than fresh fuel is ridiculous.... Unless you are planning a long motoring trip keep your fuel tank level low and add fresh fuel evey month or so. Again it is ridiculous to keep a full tank of fuel when you only use a couple of gallons a month. Most months I use less than a gallon of fuel. Keeping my tank full would mean that the average age of my fuel is about two years old. Two years is plenty of time for stuff to grow and the fuel to go bad. This full tank stuff is for stinkpotters who use a lot of fuel. I usually keep my tank at about 1/4 full which is about 5 gallons since I use less than 1/2 gallon/hour that gives me 10 hours of motoring which is often more motoring than I do all summer. I have never had more than a couple of drops of water in my fuel filter!!! I have never had an algea/bacteria problem.
A smart boater runs his tank almost dry before putting it away for the winter. Then pumps it dry. In the spring you add fresh fuel. This notion that fuel that has stabilizers and has aged over the winter is better than fresh fuel is ridiculous.... Unless you are planning a long motoring trip keep your fuel tank level low and add fresh fuel evey month or so. Again it is ridiculous to keep a full tank of fuel when you only use a couple of gallons a month. Most months I use less than a gallon of fuel. Keeping my tank full would mean that the average age of my fuel is about two years old. Two years is plenty of time for stuff to grow and the fuel to go bad. This full tank stuff is for stinkpotters who use a lot of fuel. I usually keep my tank at about 1/4 full which is about 5 gallons since I use less than 1/2 gallon/hour that gives me 10 hours of motoring which is often more motoring than I do all summer. I have never had more than a couple of drops of water in my fuel filter!!! I have never had an algea/bacteria problem.
Diesel Fuel has a relatively short shelf life ....
Diesel fuel will begin to decompose if stored over 70 degrees for more than 6 months, ... about 12 months at wintertime temperatures. Whether to change/dump the old fuel is better indicated by the condition of the tank. If the tank walls have a lot of 'crud' hanging on the walls, then the fuel is OLD, should be discarded (burn it in your oil heater at home), .... and the tank opened and cleaned. When fuel begins to decompose the 'light' fraction simply go out the vent and the heavier fractions begin to decompose and form particulate, waxes and 'goo'. The particulates 'agglomerate' into larger and larger particles that stick to the tank walls, etc. thus accelerating the process. How to test for 'old' fuel: Drain some fuel into a clear glass, hold the filled glass up to very strong light ... if the fuel has a haze (particles) then the fuel is 'old'. New fuel should be 'crystal clear' (no haze). Dont buy fuel from a marina where the fuel sits around for months and months but consider to buy your fuel from a high turnover source such as a fuel depot that caters to 'watermen' or carry it in from a truck stop. Good 'fuel info' --- http://www.bp.com.au/fuelnews/ADF1402.pdf
Diesel fuel will begin to decompose if stored over 70 degrees for more than 6 months, ... about 12 months at wintertime temperatures. Whether to change/dump the old fuel is better indicated by the condition of the tank. If the tank walls have a lot of 'crud' hanging on the walls, then the fuel is OLD, should be discarded (burn it in your oil heater at home), .... and the tank opened and cleaned. When fuel begins to decompose the 'light' fraction simply go out the vent and the heavier fractions begin to decompose and form particulate, waxes and 'goo'. The particulates 'agglomerate' into larger and larger particles that stick to the tank walls, etc. thus accelerating the process. How to test for 'old' fuel: Drain some fuel into a clear glass, hold the filled glass up to very strong light ... if the fuel has a haze (particles) then the fuel is 'old'. New fuel should be 'crystal clear' (no haze). Dont buy fuel from a marina where the fuel sits around for months and months but consider to buy your fuel from a high turnover source such as a fuel depot that caters to 'watermen' or carry it in from a truck stop. Good 'fuel info' --- http://www.bp.com.au/fuelnews/ADF1402.pdf
Diesel biocide
Lotta different opinions here, so here's mine. Gas is different, and most of my experience is diesel so I'll stick to diesel. 1) for fishermen it is a given, "keep tanks full" and for knowledgable recreational p/v skippers too. 2) I crusied my sailboat in the tropics for five years and ALL the cruisers I knew, hundreds over the 5yr period, kept their tanks full, and added biocide to kill critters. 3) Even in northern latitudes, above 38 N. the folks I know (sailors) keep tanks full, and most use biocide. 4) I have had, rust, moisture (from a tank being left 1/2 full allowing condensation), and bacteria in diesel tanks, never had "bad" diesel from letting it sit. 5) If you run your tank dry you will suck air and need to bleed the injectors; done in a controlled environment, it seems mucho work for naught. "an that's all I gotta say 'bout that" Forest Gump.
Lotta different opinions here, so here's mine. Gas is different, and most of my experience is diesel so I'll stick to diesel. 1) for fishermen it is a given, "keep tanks full" and for knowledgable recreational p/v skippers too. 2) I crusied my sailboat in the tropics for five years and ALL the cruisers I knew, hundreds over the 5yr period, kept their tanks full, and added biocide to kill critters. 3) Even in northern latitudes, above 38 N. the folks I know (sailors) keep tanks full, and most use biocide. 4) I have had, rust, moisture (from a tank being left 1/2 full allowing condensation), and bacteria in diesel tanks, never had "bad" diesel from letting it sit. 5) If you run your tank dry you will suck air and need to bleed the injectors; done in a controlled environment, it seems mucho work for naught. "an that's all I gotta say 'bout that" Forest Gump.
Filters
One more thing, when changing the Racor, don't forget the 'lift-pump-filter, most folks miss this one and it is the last line of defense before the injectors. You CAN change it each time you change the Racor, or 'water separator' filter (other brands) but is usually a Racor, and if you pour in a bit of clean diesel you don't have to bleed usually. I'll change a lift-pump-filter about every second Racor I change. I keep a wrench of the exact size of the bleed screw taped nearby so I won't need to fumble for it when needing to bleed. A good headlamp is another standard piece of equipment, keep hands free.
One more thing, when changing the Racor, don't forget the 'lift-pump-filter, most folks miss this one and it is the last line of defense before the injectors. You CAN change it each time you change the Racor, or 'water separator' filter (other brands) but is usually a Racor, and if you pour in a bit of clean diesel you don't have to bleed usually. I'll change a lift-pump-filter about every second Racor I change. I keep a wrench of the exact size of the bleed screw taped nearby so I won't need to fumble for it when needing to bleed. A good headlamp is another standard piece of equipment, keep hands free.
If full tanks are such a great idea
why do we see so many people asking about bad fuel on this site??? If I was living aboard in the tropics I would probably keep full tanks!!! Because I would be using the boat a lot and burning a lot of fuel..... BUT most of us are stuck working a job and only get to use our boats a couple of times a month... Also when you are just sailing on weekends as opposed to cruising you usually only use the motor to get out of the slip and into an open space so that you can sail...Maybe 15 minutes of run time..not much fuel use. If you do the math not much water can get into your tanks by condensation. Air doesn't hold that much water...not that much air is exchanged because the temperature in the tank doesn't change that much and the volume change with temperature isn't that much. The fuel tank is protected from temperature change in part by the boat being in water that doesn't change it's temperature very much on a daily basis. Condensation in the open air is caused by surfaces radiating heat and cooling off rapidly. This cool surface is exposed to a lot of air because as the air cools it sinks and is replaced by more moise air. This doesn't happen in a tank that is connected by a small vent hose. Even if the temperature drops 50 degrees there is only a small amount of air sucked into the tank. But it is hard, very hard to get a big temperature change in a boat sitting in water. Finally we all seem to agree that old fuel isn't as good as fresh fuel. If you only use a gallon or two a month and you keep a 25 gallon tank full your fuel is about two years old on average... But reason seldom triumphs over dogma...
why do we see so many people asking about bad fuel on this site??? If I was living aboard in the tropics I would probably keep full tanks!!! Because I would be using the boat a lot and burning a lot of fuel..... BUT most of us are stuck working a job and only get to use our boats a couple of times a month... Also when you are just sailing on weekends as opposed to cruising you usually only use the motor to get out of the slip and into an open space so that you can sail...Maybe 15 minutes of run time..not much fuel use. If you do the math not much water can get into your tanks by condensation. Air doesn't hold that much water...not that much air is exchanged because the temperature in the tank doesn't change that much and the volume change with temperature isn't that much. The fuel tank is protected from temperature change in part by the boat being in water that doesn't change it's temperature very much on a daily basis. Condensation in the open air is caused by surfaces radiating heat and cooling off rapidly. This cool surface is exposed to a lot of air because as the air cools it sinks and is replaced by more moise air. This doesn't happen in a tank that is connected by a small vent hose. Even if the temperature drops 50 degrees there is only a small amount of air sucked into the tank. But it is hard, very hard to get a big temperature change in a boat sitting in water. Finally we all seem to agree that old fuel isn't as good as fresh fuel. If you only use a gallon or two a month and you keep a 25 gallon tank full your fuel is about two years old on average... But reason seldom triumphs over dogma...
Condenation ...
Condensation is actually a misnomer .... actually what is occurring is a chemical equilibrium of mixtures and that fresh fuel is relatively dry in comparison to normal atmospheric conditions is the 'drive' that causes moisture to 'dissolve and diffuse' into the fuel oil .... plus the little bit of 'condensation' that occurs on the tank walls. I worry about neither as I have a desiccant filled (dyed) silica gel canister on the vent line to my tank. This absorbs all the moisture (to -40 deg. dewpoint) that gets drawn into the tank (I have a large black iron tank and therefore am quite cautious with water/rust). Dyed silica gel is available from 'hobby shops' that cater to the 'flower drying' crowd. The dyed gel changes from blue to pink when saturated. It can be 'regenerated' by putting into an oven at 350 degrees for 6 hours.
Condensation is actually a misnomer .... actually what is occurring is a chemical equilibrium of mixtures and that fresh fuel is relatively dry in comparison to normal atmospheric conditions is the 'drive' that causes moisture to 'dissolve and diffuse' into the fuel oil .... plus the little bit of 'condensation' that occurs on the tank walls. I worry about neither as I have a desiccant filled (dyed) silica gel canister on the vent line to my tank. This absorbs all the moisture (to -40 deg. dewpoint) that gets drawn into the tank (I have a large black iron tank and therefore am quite cautious with water/rust). Dyed silica gel is available from 'hobby shops' that cater to the 'flower drying' crowd. The dyed gel changes from blue to pink when saturated. It can be 'regenerated' by putting into an oven at 350 degrees for 6 hours.
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