Dirty Fuel

[Rasselas36]

I’m having to get my fuel polished every year. I have neighbors with a 2003 Catalina and 2000 Beneteau and both have never had their fuel polished. I have replaced the o-ring on my fuel cap several times.
I buy fuel from the same Marina as they do.
It is exhausting changing the fuel filters and expensive ($450) to get fuel polished.
Three years ago, we removed my tank and had it pressure washed.
Any help is appreciated.

 

[Don S/V ILLusion]

Moisture getting into tank vent?

 

[mikeracca]

What does the tank look like inside? Have you been using any biocide or anything like that to help treat your fuel? Also what type of fuel filtration systems do your neighbors use? They may have better filters and thus they are not seeing the same issues as you.

 

[dlochner]

If you are not using [Baobab] Biobar JF with every fueling, you should. It will hold the buggers at bay. Do you fill the tank each fall before laying it up?

The issue is moisture, there are filters to put on the vent line that are effective at preventing moisture from entering the tank. Check Practical Sailor for a review.

In what condition is your fuel fill hose? Might it be old and somehow allowing moisture to enter the tank?

Edit: I just noticed that spell check wanted you to put a Baobab tree in your fuel tank, I think that would be poor advice. Put Biobar JF in.

 

[SycloneDriver]

That's a lot of polishing!

What are your symptoms?
What are your fuel filters collecting?
What is your polishing vendor telling you?

I have polished my share of diesel fuel as a generator tech. We mostly do it as a preventative measure. For $450 you could build a small polisher. A polisher is primarily a pump, filters and hose.

 

[jssailem]

exhausting changing the fuel filters

What type of fuel filter system are you using?
FWIW... I have a Racor 500M primary filter. I added it to the boat.

It takes less than 10 minutes to change a filter.
Here is what a clogged filter from dirty fuel looks like...

Filters run about $10.
This one caused the engine to be starved of fuel. The engine shut down. I do not let it get this bad anymore. Using Biobor JF each time I fuel has cleaned the fuel in the tank and I no longer have a clogged filter. I change it maybe once a year now. No more fuel issues.

 

[Dalliance]

Ditto everything dlochner said and I would add: check your fuel vent line configuration. Does it go straight down from the fuel vent to the tank? If so, that’s bad. It needs to go up a few inches just inside the vent fitting so any water that enters the vent will drain back out instead of going down into your fuel tank. This can be accomplished by re-routing the vent hose or by changing the fuel vent fitting.

 

[Ralph Johnstone]

It needs to go up a few inches just inside the vent fitting so any water that enters the vent will drain back out instead of going down into your fuel tank.

Good advice but I would stretch it a little bit more and raise the vent line loop as high as it will go and then drop down to the tank.

Definitely something funny going on with your fuel setup. I check my fuel every few years through a small sampling port using a Pela oil suction pump.

The pump has a clear tube which allows me to check for water and crud. Very small amount of water and black bits on occasion. I believe what keeps it clear is Biobor JF biocide.

I'm definitely not as conscientious as others when it comes to fuel as I replace my primary filter every five years (looks clean) and never bother to fill my tank before winter sets in. I motor about 100 hr/year. Maine Sail posted and article a few years back which demonstrates that filling your tank to avoid condensation was 100% . Made a lot of sense as I see little to no water in my fuel tank.

 

[Davidasailor26]

Maine Sail posted and article a few years back which demonstrates that filling your tank to avoid condensation was 100% .

Just to clarify - Maine’s article ( Does an Empty Marine Fuel Tank Condensate? - Marine How To ) was specific to an empty tank, not one partially filled with diesel that could trap water below its surface. See the discussion between Maine and thinwater at Old diesel fuel for details.

 

[jssailem]

These discussions about filters and old fuel are good at this time. With the cost of diesel rising, the idea of pumping old fuel out and discarding it can hurt the cruising kitty. Especially true when we discover that the fuel was still usable.

Having to polish your fuel yearly is also unacceptable.

 

[Ralph Johnstone]

was specific to an empty tank, not one partially filled with diesel that could trap water below its surface.

The inspection of my fuel tank is then, an even a more severe test than @Maine Sail 's testing of An empty, clean and dry 20 gallon aluminum marine fuel tank as discussed in his article Does an Empty Marine Fuel Tank Condensate? - Marine How To . My tank would always have a blanket of diesel fuel to avoid the evaporation of any condensate which previously collected. I've never found any water (beyond a drop or two) in my periodic sampling over the last 24 years. The few drops of water I do see on occassion may just as well been emulsified in the fuel received in my tank from the supplier.

Theoretically, yes it's possible but highly unlikely that significant condensation will occur in a sailboat fuel tank which is left with a minimum amount of fuel over the winter. Definitely not worth the effort of considering whether or not to fill your tank with fuel at the end of the season.

 

[Barnacle Bill]

Polishing your fuel is fine. I have a polisher and have used it with clear hoses so I can see if there's junk in the fuel. But, there's also the pick up tube, which can get clogged and also fuel hoses go bad and need to be replaced. Old hoses can compress under pressure. And, even if you polish the fuel, that doesn't rid the tank of crap lying on the bottom. Beyond using a product like Killem' or another additives to kill algae, you might have to bite the bullet and clean the tank. Usually there are the primary filters, like the Racor shown above, and also there usually is a secondary filter too. The correct filter element is essential.

 

[Ward H]

Definitely not worth the effort of considering whether or not to fill your tank with fuel at the end of the season.

I normally do fill the tank at the end of the season simply because I’m also there to pump out the holding tank. I didn’t last year due to the tranny failure.
I’ll be paying for that when I fill up tomorrow.

 

[Ralph Johnstone]

I’ll be paying for that when I fill up tomorrow.

Filling your fuel tank is getting to be like playing the stock market .