Good Diesel & Bad Diesel Poll

[Wotname]

I keep reading posts on CF about contaminated diesel and fuel tank problems and filters clogging up and so on. The way some talk, it seems to be almost a daily occurrence. I have never had a fuel issue (yet ) and I got to wondering just how many of us have these issues and perhaps more importantly, how many don't.

Of course, we only hear about the bad times, no one posts that today I used the engine and didn't have any problems so here is your chance to let us know how well it goes for you!

For those who don't have any problems, do you have secrets to share?

For instance, while I never really care about the age of my fuel in the tank (often around a year old), I do try to keep the tank topped up as much as possible and I do tip in a bit of fuel treatment each time I add fuel. I also drain a cup or so of fuel from the sump every time I add fuel or if the boat has sat for more than a month or so.

I have never polished fuel and rarely change the filter so perhaps my first fuel issue is lurking nearby But then again, I have only ever filled up with clean fuel - except in Indonesia where clean fuel isn't an option - at least it wasn't where and when I was there

Looking forward to your tips!

[Seaworthy Lass]

We don't worry about the level of fuel in our tank. Capacity is 1000 litres and it is rarely more than half full (we simply don't use much fuel).

Mainesail has conducted some tests on condensation in empty tanks and found that this was not an issue in his study:
Does An Empty Tank Condensate? Photo Gallery by Compass Marine How To at pbase.com

A few of our tips:
- We always look at a sample of fuel in a glass jar before filling
- We fill with a filter
- Fuel additive is used at the time of filling (Grotmar) with preventative not shock dose
- We polish our fuel almost daily for several hours (pick up from the very bottom of the tank is filtered through a large Raycor unit with a 10 micron filter).

Both the primary and secondary fuel filters look spotless whenever they are checked.

For a maintenance system like this to work successfully, I think the tank needs to be reasonably clean to start with.

SWL

[capngeo]

Twice: once the fault of the supplier, once my own.

Years ago (mid 90's) we had a terrible drought in Florida. Lake Okeechobee was at an all-time low and I had a trip across planned. With the extremely low controlling depth, very few diesel (larger) boats were making the trip. I pulled into Roland Martin's to top off before Route 1.

Made it into the lake and the filters were overwhelmed with water. Engines shut down in a rather narrow channel. A quick drain (thank you Racor for easy drains), and we were off..... sort-of...... about 6 more drains before we made the other side of the lake. Called Martin's to bitch and were told that we were the first diesel customer in MONTHS and they would check their tank (gee, thanks?).

The second time, in my sail boat, I forgot the additive, and stored the boat for a 6 month period. The fuel was BLACK with algae when I got back, and clogged filters in 5 minutes. After exhausting my on-board supply of filters, I got towed back to the dock bu TowBoat/US and cleaned the tank.

[carstenb]

We've never had a problem, although we've only refuled here in the Baltic where the fuel is clean. I do carry a Baja filter in case I'm ever in doubt. We try to only refuel in large marinas where the diesel never gets old and I also add a little antibio when we fill the tank (about once per year - we sail mostly)

[Snowpetrel]

Only had problems twice. Once on a known bad tank that we where trying to burn off before cleaning. We only got about 10 minutes before the first filter clogged. I think they where 2 micron primaries. We went through a few filters pretty quickly! probably should have had 30 micron prefilters. We did have 2 other good tanks full of diesel, just wanted to use up the old stuff. We filtered the bad tank though sheets of kitchen paper into an empty tank (the tissues got black real quick!) I think we used a few rolls to do the whole tank (about 300 liters or so) but after that it was fine.

The other time was a delivery. lots of water in the tank, we had to drain the water trap every hour or so for a while. Of course it was lumpy and not much fun in Bass Strait and Banks strait..

I normally carry a jerry can of good fuel, and have a fuel hose long enough to gravity feed it to the engine on deliveries on unknown boats, and on one delivery we decided not to use the main tanks and just ran on jerry cans.

But all said and done I've really had limited problems with bad fuel, touch wood! much more issues with air in the line.

[carstenb]

Just a further note, I change my water separator filters every year in the springtime - so far there has been no water in them at all- i leave the tank full over the winter.

[ctl411]

Great thread/poll, I've often wondered also about all the fuel problems. Never had a problem except for running out a couple times. I also only buy from high volume sellers and add additives as needed.
Not always a option for some that have larger cruising areas.

[sanibel sailor]

Originally Posted by Seaworthy Lass

We don't worry about the level of fuel in our tank. Capacity is 1000 litres and it is rarely more than half full (we simply don't use much fuel).

Mainesail has conducted some tests on condensation in empty tanks and found that this was not an issue in his study:
Does An Empty Tank Condensate? Photo Gallery by Compass Marine How To at pbase.com

I have heard for years about keeping fuel tanks full to avoid condensation
in the air in the tank. It seems to make sense and is widely quoted as
fact, but no one says the extent of the problem. Damp air gets sucked into the tank, then the water condenses as it cools. I have always wondered if this was a significant source of contamination. I was thinking that a valve on the vent may be reasonable, so I did some physics homework tonight. Turns out the amount of water coming in is likely pretty minute.

Assume:
A generous temperature change from 23 degrees F to 59 degrees F (-5 to 15 Celsius) results in a volume of air exchange of 7.5% (BTW 0F to 75F makes it 16%)

Assume:
100 gallon air space in tank
100% relative humidity of the warm air with this temp change gives 3.3
grams of condensed water or about half a teaspoon from the entire air volume, but only about a quarter of a gram for every thermal cycle or about 1 1/2 teaspoons per month.

If the relative humidity is 70%, the amount goes down to about 60% of this.

My conclusion-for moderate daily temp fluctuations in relatively moderate
humidity in the winter months, given my 32 gallon diesel tank has say ten
gallons of fuel in it, there is probably about a teaspoonful of water all
winter. This amounts to about a drop of water per day. Leaky deck fill O-rings are much more likely culprits.

[laika]

I've gone thru about 20 racor filters since buying my boat a few years back. When I finally pulled out the fuel tank and cut an inspection port in it, it was fairly clean, so I guess I must have already polished the thing thru my engine filters..

I installed a fuel polishing system from the tank sump and run through a large commercial grade 5micron filter. In my short experience, problems with the engine have nearly always been fuel related, so it's nice piece of mind to ensure I'm now giving the engine clean fuel.

[a64pilot]

Only once and it was on delivery after purchase, I kept getting what looked like Tofu clogging the fuel line, never did get to the filters. After getting through that, I've always used Biobor and no issues since. I have no inspection port and can't install one.
Much as we hate to motor, I think regularly turning the fuel helps. As stated replace the O ring in the fuel cap every few years and I've seen the vent in a few boats be mounted in a manner that lets water in in heavy seas or heeled over.
I think water is the culprit, if you can keep your fuel dry and use the biocide you'll eliminate a lot of the problems


Sent from my iPad using Cruisers Sailing Forum

[carstenb]

Originally Posted by sanibel sailor

I have heard for years about keeping fuel tanks full to avoid condensation
in the air in the tank. It seems to make sense and is widely quoted as
fact, but no one says the extent of the problem. Damp air gets sucked into the tank, then the water condenses as it cools. I have always wondered if this was a significant source of contamination. I was thinking that a valve on the vent may be reasonable, so I did some physics homework tonight. Turns out the amount of water coming in is likely pretty minute.

Assume:
A generous temperature change from 23 degrees F to 59 degrees F (-5 to 15 Celsius) results in a volume of air exchange of 7.5% (BTW 0F to 75F makes it 16%)

Assume:
100 gallon air space in tank
100% relative humidity of the warm air with this temp change gives 3.3
grams of condensed water or about half a teaspoon from the entire air volume, but only about a quarter of a gram for every thermal cycle or about 1 1/2 teaspoons per month.

If the relative humidity is 70%, the amount goes down to about 60% of this.

My conclusion-for moderate daily temp fluctuations in relatively moderate
humidity in the winter months, given my 32 gallon diesel tank has say ten
gallons of fuel in it, there is probably about a teaspoonful of water all
winter. This amounts to about a drop of water per day. Leaky deck fill O-rings are much more likely culprits.

Thank you for this. I've practiced having a full tank inthe winter (our boat stays inthe water up here in Denmark) and never had a water problem, but often wondered how much condensation actually occurs.

Another culprit re water is filling your tank in places that do not sell much fuel and if htey have an above ground tank, that isn't cleaned yearly, then there is a chance you will get contaminated fuel

[sailorboy1]

I've only have a problem once. It did happen early in the season the only time I hadn't filled the fuel tank in the Fall and left in partially filled all winter.

[ytquest]

I have had maybe 3 problems with fuel, but they all stemmed from not using Stabil when not using the engine for long periods or taking on fuel for extended time. I hold 200 gal's. and the solar panels have work great for the last 22 years. Air leaks in the fuel system has been my biggest problem.

[Cheechako]

How often have you experienced significant bad fuel problems?
Does this include taking preventive measures? What if I have the tank cleaned and fuel polished when ever I buy a boat with old fuel or an unknown past? Was that a bad fuel issue?

[roygee]

Originally Posted by sanibel sailor

I have heard for years about keeping fuel tanks full to avoid condensation
in the air in the tank. It seems to make sense and is widely quoted as
fact, but no one says the extent of the problem. Damp air gets sucked into the tank, then the water condenses as it cools. I have always wondered if this was a significant source of contamination. I was thinking that a valve on the vent may be reasonable, so I did some physics homework tonight. Turns out the amount of water coming in is likely pretty minute.

Assume:
A generous temperature change from 23 degrees F to 59 degrees F (-5 to 15 Celsius) results in a volume of air exchange of 7.5% (BTW 0F to 75F makes it 16%)

Assume:
100 gallon air space in tank
100% relative humidity of the warm air with this temp change gives 3.3
grams of condensed water or about half a teaspoon from the entire air volume, but only about a quarter of a gram for every thermal cycle or about 1 1/2 teaspoons per month.

If the relative humidity is 70%, the amount goes down to about 60% of this.

My conclusion-for moderate daily temp fluctuations in relatively moderate
humidity in the winter months, given my 32 gallon diesel tank has say ten
gallons of fuel in it, there is probably about a teaspoonful of water all
winter. This amounts to about a drop of water per day. Leaky deck fill O-rings are much more likely culprits.

Sounds like good government figures to me. Try to glass in a hole in a tank when the clouds are drifting over; you will find that the tank breathes all the time.