Fuel polishing - how often?

[Old Swampy]

I recommend that you add a pressure gauge to your polisher between the pump and the filters so that you discern when the filters need changing. My pump maintains 7 psi with clean filters, and my filters came with a max pressure of 20 psi. I have seen the black crap and I believe.

[laika]

Originally Posted by rhubstuff

=1 for xlantic. If you just polish fuel in layup or at the dock, you're not getting the crud out of the bottom and corners. The fuel should be agitated, mechanically if necessary, to force foreign material in suspension so the polisher can filter it out of the system. That said, only a small amount of all the fuel that runs through the fuel pump is sent to the injectors; the rest is returned to the tank, having been polished by your regular fuel filters. So what is the point of a separate filtering system, except in places where you actually expect to get bad fuel?

I like running the polisher under sail when it's choppy. When the engine comes on I know my primary filter wont be sucking up a bunch of crap that just dislodged from the tank walls.

A good polishing system also gives you a secondary and immediate means of getting fuel to the engine if your primary filter does clog up. Just flip a valve and the polished fuel can get fed into your engine pickup line.

There is , of course, no substitute for a clean fuel tank.

[DeepFrz]

Originally Posted by holmek View Post
I'm having trouble understanding this whole paranoia.

Is it paranoia when your engine stops in a seaway because the fuel line is plugged with black tar like substance? Or would adding a fuel polishing system be a prudent action to take to prevent such a situation from happening?

I answer yes for the second question above. So call me paranoid.

There have been quite a few members of this forum that have suffered through fuel/filter problems, some like myself in a seaway. I haven't read one thread that said anything like "I added a fuel polishing system after cleaning my tanks and my filters are now all plugged up". Not one. I have seen threads that said something like "I cleaned my tanks and there was a pile of sludge on the bottom and stuck to the walls of the tank".

[Muckle Flugga]

Originally Posted by Toys_with_time

Yes serviced injectors, dumped all the fuel (properly), replaced engine filters and pre filters / water traps, cleaned the empty tank and started with a fresh fill.

UV filter? For bugs? Hadn't heard of that.

Yes. For bacteria. Actually the most useful bit of my particular filter.

[noelex 77]

The most useful polishing time is when the tank has been stirred up sailing. I usually run the polishing pump most of the time sailing.

I also run it whenever I have excess power so it is often on 5-6 hours a day. I suspect at anchor it is not doing much, but there is an argument that water is best removed by allowing the fuel to settle.

In other words solid crud is best removed when the tank is agitated sailing and water is best removed when the boat is still.

It is very difficult to know, but my fuel is spotless with the polishing system running frequently

[Pete7]

Originally Posted by Xlantic

But, in a boat, when you have enough motion from waves, the crud is disturbed, floats up, and is sucked by the pick-up tube. When this happens the filters are overwhelmed, and changing them doesn't solve the problem because the new one gets clogged by the now disturbed crud in the tank. As you can imagine, this happens at the worst possible time, in a seaway. (Ask me how I know this.)

I disagree, my experience is the crud sinks to the bottom of the tank and forms a consistency of custard. This doesn't mix with diesel and can only be disturbed by physically dislodging it either mechanically or with diesel under high pressure and flow rates which are unlikely to be available on a yacht.

You can see the diesel is clear in this photo and the crud attached to the steel tank.



The tracks in this photo were caused by a previous attempt to clean the tank with the fuel polishing hose moving around in a random pattern to stir up the crud. It didn't work.

Originally Posted by Xlantic

Thus, many of us, particularly with older boats, are paranoid about this issue. My personal opinion is that polishing will not a guarantee the problem is solved. i believe the definitive solution, at least for an older boat, is day tanks.

Agreed, fuel polishing may have a roll in maintaining the fuel but it is not a silver bullet. Been there and changed my opinion on fuel polishing, I still do it but its only part of the work which includes chemicals, polishing, regular replacement fuel caps and seals to keep the water out in the first place and finally inspecting the tank.

Pete

[Pete7]

Originally Posted by noelex 77

The most useful polishing time is when the tank has been stirred up sailing. I usually run the polishing pump most of the time sailing.

I think the problem isn't helped by those of us who keep tanks topped up to avoid the risk of condensation, a risk Nigel Calder doesn't believe exists btw. There just isn't a washing machine action going on in a full yacht tank. A 1/4 full tank would be be different.

Assuming the fuel pick up is just off the bottom of the tank perhaps the solution is a dozen large glass marbles rolling around which are too big to get under the pick up.

Pete

[DeepFrz]

Posted by Pete7: Agreed, fuel polishing may have a roll in maintaining the fuel but it is not a silver bullet. Been there and changed my opinion on fuel polishing, I still do it but its only part of the work which includes chemicals, polishing, regular replacement fuel caps and seals to keep the water out in the first place and finally inspecting the tank.

Absolutely...maintenance of the fuel system. There may not be one silver bullet but proper maintenance will ensure a trouble free system.

[Muckle Flugga]

Originally Posted by Pete7

I think the problem isn't helped by those of us who keep tanks topped up to avoid the risk of condensation, a risk Nigel Calder doesn't believe exists btw. There just isn't a washing machine action going on in a full yacht tank. A 1/4 full tank would be be different.

Assuming the fuel pick up is just off the bottom of the tank perhaps the solution is a dozen large glass marbles rolling around which are too big to get under the pick up.

Pete

Interesting idea… bit loud though don't you think? Anyhow, for me the solution is partly the polisher, and partly the down and dirty job I do around once every 18 months (or more if necessary) of just manually cleaning and polishing the fuel tanks.

[noelex 77]

If your tank is very dirty you need to physically clean the tank.

However, offshore sailing produces some brutal sloshing of the fuel. This with a pickup at the bottom of the tank and frequent use of the polishing pump will maintain a clean tank and reduce, or eliminate the periodic cleaning of the tank.

Cleaning the tank is a major job, so the elimination or even reduced need to do this will justify the advantage of a polishing system for many users.

What is less clear if a polishing system will gradually clean a dirty tank. I think there is some evidence that frequent use will do this in mild to moderate cases, but this is far from definitive.

My own view is that a polishing system with a pickup at the bottom of the tank, used frequently, will keep the tank clean and the diesel water free if you take so e other sensible precautions. If your tank is mildly dirty the polishing system will rectify the problem, but any more than a mild problem and the tank should be physically cleaned.

[Pete7]

I think that is a fair comment. Interestingly other than a wisp of black gunk in the water separator at the end of each year. I wasn't aware of the condition on the inside of the tank above. I only looked inside out of curiosity

[colemj]

That crud looks like a biofilm. Polishing will never remove that, but would help to prevent it from occurring in the first place by removing the water necessary for growth, and the nascent bio stuff that hasn't attached.

Mark

[s/v Jedi]

When you recirculate fuel in the same tank the rule of thumb is to pump an amount of fuel 5 times that of the tank contents for a full polishing cycle.

I have a sump welded under my aluminium fuel tanks and pick up the fuel from there. If you don't have that, you need a separate pickup-tube that goes all the way down to the bottom. Many attach a small piece of hose that is an inch or two too long so that it bends to horizontal right on the tank bottom.
For storage I add the enzyme based StarTron and circulate through every filter and engine. You see the color change. When done, you can leave it for a long time, I did for up to 8 months and never a problem.

The picture with the crud on the tank bottom: use a pressure washer that is fed with diesel instead of water. This is how commercial polishers do it.

[Nicholson58]

There is a similar thread on CF for fuel polishing. Fuel Filtration Systems - Page 7 - Cruisers & Sailing Forums


After much study and an expensive main pump rebuild, We are adding Franz filters (similar to Pacific Cost Filters). I will have one on each crank case and one for the fuel system. These run any time the engine or generator are on. The fuel system filter will also run at will by aux switch. No fuel will enter an engine that has not been filtered to 1 micron.


Search on trucker sites notes that many no not ever change crankcase oil with one of these installed - over 100,000 miles.


Great articles here:


https://oursojourn.files.wordpress.com/2008/04/fuelmanagementsystemarticlewithpicsv608072005.pdf


http://www.trawlersandtrawlering.com/howto/captnwil.html

[ErikFinn]

Originally Posted by Xlantic

I think the important difference is that farm tanks don't move and boat do. I believe over the years, decades for many of our boats, crud accumulates in the bottom of the tanks. The source of this crud (asphaltenes from the breakdown of the fuel, "algae" or some biological by-podruct, water or who knows) is better left for another discussion. This stuff can accumulate and sit in the bottom of the tank, undisturbed, because the pick-up point for the fuel is above it.

But, in a boat, when you have enough motion from waves, the crud is disturbed, floats up, and is sucked by the pick-up tube. When this happens the filters are overwhelmed, and changing them doesn't solve the problem because the new one gets clogged by the now disturbed crud in the tank. As you can imagine, this happens at the worst possible time, in a seaway. (Ask me how I know this.)

Thus, many of us, particularly with older boats, are paranoid about this issue. My personal opinion is that polishing will not a guarantee the problem is solved. i believe the definitive solution, at least for an older boat, is day tanks.

Yup, if your farm tractor engine quits in "choppy lands" it's not a big deal, good occasion to make a nice hot cuppa (for example)

If your boat's engine quit's in choppy seas, it's a whole different scenario.