Fueling up prior to non-use

[Winemaker2]

Originally Posted by MrMark52

Moisture vapor in the atmosphere does and will find a path to the cold fuel in the tank when you have long periods of cold followed by warmer weather.

A full tank has less room for moisture vapor to collect and surface area to condense against.

I agree that filling can be beneficial where moisture is generally high... seashore, etc.
When the furl is cold and outside air is warm and humid there us little / no inspiration into the tank so no condensation. If/when the warmth persists the fuel temp rises gradually and liquid / vapor above it expands and the venting is out of the tank.
As the temps decrease the moisture content is decreased (cold air not capable of holding as much moisture as warm). Fuel temp eventually decreases but will lag the air temps due to shading and energy input reqd to raise liquid temps vs air temperature. So when fuel / vapor is cooling and inspiration outside air the air is already cool and holds less moisture.
I have stored boats and MH for months in relatively dry & cold NE and had no, zilch, nada water found in water separating filters.
Deep south, seashore, etc is different.
That said there is no downside to filling the tank.

[Flyer15015]

I fill my gasser to the rim and add Stabil when I put her away for the winter and I'm in cold dry Colorado.
But that's just me.

Mike in Colorado

[bentjm]

Originally Posted by BayRunner

It all adds up over time. In my days of working Coast Guard Search and Rescue, I assisted countless boaters stranded with a fuel water-separator full of water.

Well, they should have replaced or drained those filters.

I have owned over 20 boats from 16 to 90 feet. Currently have a 90 foot houseboat and a 24 foot runabout. Most water in the fuel comes from the marina fuel pump, not from condensation.

If condensation was that big of a problem in RVs, then all older RVs would have fuel tanks full of water.

[Triangle Drifter]

Originally Posted by pasdad1

Add BioBor-JF and fill the tank full. I believe this is the best course of action.

Attachment 380669

I have been using this product in my diesel powered boats during winter storage since 1986. Since 2007 same with my diesel truck which sits unused November to April.

Put this stuff in. Fill the tanks. The short run to the storage place gets it through the whole system. Say bye bye for six months.

It is not all that readily available off the shelf at the auto stores but can be found in marine stores where there are many diesel boats in the area &, of course, Amazon.

[Chargerman]

Originally Posted by bentjm

Well, they should have replaced or drained those filters.

I have owned over 20 boats from 16 to 90 feet. Currently have a 90 foot houseboat and a 24 foot runabout. Most water in the fuel comes from the marina fuel pump, not from condensation.

If condensation was that big of a problem in RVs, then all older RVs would have fuel tanks full of water.

So if the water came from the fuel pump then how do you think it got there.....condensation in the storage tank. I have a boat in Fl and I didn't fill the tank when I put it away two years ago and last Winter I ended up constantly daring water from the separator. I alway fill the couch with fuel and use Biobor when I put it to bed for the Winter and will never let the boat sit again for the off season without a full tank of fuel.

[Iceclimber]

Count me as a non believer on this concept, but every time I weigh in on this or gas fuel additives (yes diesel needs some additives for specific scenarios) or any topic that has no science to support it, the threads end up in an exhausting argument. I will say the concept of having a fully fueled escape/support rig makes the most sense of all, so sure keep it ready for action. However I have never encountered any evidence with my mark one eyeball supporting condensation is a problem in a non empty tank of any variety. All big boats have fuel tank vents for a reason, and the very reason fuel/water separators exist with those handy drains on the bottom. The more diesel you store the more you need to take care of it. This from a cat diesel generator professional that spent a lot of time treating full tanks of diesel. With gas having more of it is even less appealing. However like any other topic that is not scientific and mostly opinion, to each their own. (even that comment seems to irritate people lol)

[Iceclimber]

Originally Posted by Chargerman

So if the water came from the fuel pump then how do you think it got there.....condensation in the storage tank. I have a boat in Fl and I didn't fill the tank when I put it away two years ago and last Winter I ended up constantly daring water from the separator. I alway fill the couch with fuel and use Biobor when I put it to bed for the Winter and will never let the boat sit again for the off season without a full tank of fuel.

Then someone is buying gas in the wrong place. Marinas that are trustworthy bring in fresh gas constantly and test constantly and also have properly vented systems and separators and/or diesel fuel polishing systems which are in fact FILTERS. Diesel is a pretty low grade of fuel to begin and sure in remote areas you might get some crap fuel but again, this is why filters and separators exist. If you simply test a sample of gas from any source - meaning let it sit in a glass jar and see if it seperates that is all the science one needs.

[bentjm]

Originally Posted by Chargerman

So if the water came from the fuel pump then how do you think it got there.....condensation in the storage tank. I have a boat in Fl and I didn't fill the tank when I put it away two years ago and last Winter I ended up constantly daring water from the separator. I alway fill the couch with fuel and use Biobor when I put it to bed for the Winter and will never let the boat sit again for the off season without a full tank of fuel.

I don't know, I would have to see the setup at that particular marina.

Is your boat kept in the water, on a trailer, or in dry storage?

The science simply does not support the idea of massive condensation.

[Ray,IN]

Originally Posted by bentjm

I don't know, I would have to see the setup at that particular marina.

Is your boat kept in the water, on a trailer, or in dry storage?

The science simply does not support the idea of massive condensation.

What science? Please post a link to support that statement. BTW, it is not "massive" condensation, it depends entirely upon local ambient humidity levels. For instance, the SW portion of the U.S.A. would have little humidity to condense, The NW coast portion would have many times more humidity.

[Winemaker2]

Originally Posted by bentjm

I have owned over 20 boats from 16 to 90 feet. Currently have a 90 foot houseboat and a 24 foot runabout. Most water in the fuel comes from the marina fuel pump, not from condensation.

I agree that boats are different than MHs when it cones to water in fuel.

The difference is in the style and location of fuel fill caps.
Most boats have fuel fills on an exterior deck surface and many more or less horizontal. They keep moisture out with on O'ring seal. That water is most often rain water or wash water finding its way past a less than optimum / yrs old o'ring.
No argument some fueling locations that sell / dispense low volumes of fuel and may be subject to related issues it is the lack of care in handling and preventive maintenance that is the root cause of the water.

[Chargerman]

Originally Posted by bentjm

I don't know, I would have to see the setup at that particular marina.



Is your boat kept in the water, on a trailer, or in dry storage?



The science simply does not support the idea of massive condensation.

My boat is kept covered on my lift at my home in SW Fla. I do get fuel at one of the two places on the island and they have a lot of turnover during season. All I know is that there wasn’t any sign of water in the fuel when I used the boat prior to storing it and when I returned after the Summer months I had nothing but issues. Although it’s not difficult to remove the water from the separators, it is a bit painful removing the engine covers and the water separator bowls and dealing with the water. I certainly would prefer not leaving it with 500 gallons of fuel but I won’t chance it again.

[MrMark52]

Originally Posted by Winemaker2

I agree that filling can be beneficial where moisture is generally high... seashore, etc.
When the furl is cold and outside air is warm and humid there us little / no inspiration into the tank so no condensation. If/when the warmth persists the fuel temp rises gradually and liquid / vapor above it expands and the venting is out of the tank.
As the temps decrease the moisture content is decreased (cold air not capable of holding as much moisture as warm). Fuel temp eventually decreases but will lag the air temps due to shading and energy input reqd to raise liquid temps vs air temperature. So when fuel / vapor is cooling and inspiration outside air the air is already cool and holds less moisture.
I have stored boats and MH for months in relatively dry & cold NE and had no, zilch, nada water found in water separating filters.
Deep south, seashore, etc is different.
That said there is no downside to filling the tank.

Winemaker2 -

Yes, the ability of air to hold water as it cools is decreased - BUT, given a specific volume of air (the vacant room in the fuel tank above the fuel level) at a specific temperature, with a given # of grains of moisture in that air - as that air cools, it’s dew point goes up - to the point that if the fuel tank and fuel get cool enough, will cause condensation.

To all - I’m not so sure the low levels of condensation in the tank is as much detrimental to engine operating as much as it is to the corrosive affects of water to system components.

Another factor - as fuel cools, it shrinks, and the vacuum inside the fuel tank draws air into the tank.
And, as fuel warms up, it expands - hence the need for EVAP systems on vehicles using the more volatile gasoline. But for the moment that said air is inside the tank (cold engine start) any moisture in that air is quickly consumed thru engine vacuum.

Also keep in mind as part of the discussion - especially in trying to compare fuels and moisture content - most gasolines for automotive use today are blended with up to 10% ethanol. Ethanol loves water - but there limits to how much water a tank of gasoline can “keep in suspension” (so to speak).

So - arguments relative to gasoline will be different than arguments relative to diesel because there are differences in the characters and affects of the two fuels.

I do know that the previous owner of our current coach said that after 2 fuel pump failures and seeing the corrosive buildup (he said stalactites) inside the fuel tank, replacing the fuel pump once again, along with having a stainless steel tank made. This on an ‘02 coach that had 37k miles on it when we bought it.
Not real sure what he or the 1 or 2 PO’s we’re putting in this coach for fuel, nor their fuel filling practices.
But we keep the gas tank full after every trip (gasoline, not diesel) because in the fall and spring in North Texas, we get temperature swings that could cause condensation to occur in a near empty tank because there is less mass to chill over night which could then allow what water vapor there might be in the tank to condense.

[caninecop]

Originally Posted by Alpine36

Fill the tank. I do for two reasons...

One, always ready to roll at a moments notice.

Two, 100 gallons of diesel will run the generator a long time in the event of an extended power outage. (We also keep the propane tank relatively full)
Since our house is all electric heat this has proven a most comfortable option.

I do the same thing with our all electric RV, living in southeast Arizona where humidity is not a big problem. We are hooked into 50amp shore power at home, I don’t recall every losing power at home in the wintertime due to weather. If it does happen it’s nice to know we can go to the RV and stay warm until the power comes back on.

[MrMark52]

Originally Posted by caninecop

I do the same thing with our all electric RV, living in southeast Arizona where humidity is not a big problem. We are hooked into 50amp shore power at home, I don’t recall every losing power at home in the wintertime due to weather. If it does happen it’s nice to know we can go to the RV and stay warm until the power comes back on.

Funny - in todays world of electrically powered vehicles, I had to think for a minute about what you were saying “I do the same thing with our all electric RV . . . . . “.