Please send any
comments to me.

This page updated:
June 2011


Don Casey's "Fuel System Maintenance"
"Feeding the Beast" article (diesel fuel system) by Don Casey in Nov/Dec 2000 issue of Blue Water Sailing magazine

From McRory's Logbook:
[My boat] is fitted out with two RACOR primary fuel filters plumbed in parallel, with selection valves. Having them plumbed in parallel means I use one filter at a time. If it gets plugged or water gets in the system I can switch to a different tank and filter without shutting the engine off. These are the filters that have the glass bowls and drains on the bottom so you see what's coming up from your tanks, and sometimes it isn't diesel fuel.

From SG on Cruising World message board:
Get a Racor filter. You can "see" the water. You can see the color of the fuel (sometimes algae, or worse). You can add a vacuum gauge and you're done -- you'll change the filter when you need to -- not just to do it. It might be two years between changes -- or two months, depending on where you get your tank filled or what you're trying to grow in it.

From Frank Burrows on The Live-Aboard List:
> What pressure range of fuel vacuum gauge should I buy ?

The standard gauge you will find is 0 to 30". My boat runs at 0 with new filters. I usually change them when they get to 7 or 8 inches. I discovered that it was reading 15" once but the engine was still going strong. If you could find a 0 to 20" it might be a little better but these would be hard to find and I doubt you would see much difference.

Racor has their vacuum gauge color-coded Red for Normal 0-10", Caution 7-10" and Danger 10-15".

From Norm on the IRBS live-aboard mailing list:
Check with Racor for the correct size of Racor. If the Racor is too big for the flow, it will not have the proper swirl action in the bottom of the unit to coalesce the water.

From Norm on the IRBS live-aboard mailing list:
... arrange things so that there will never be any water in the tank, easy to do when making a new tank. Have the tank builder weld a threaded fitting such as a pipe coupling cut in half, onto the bottom of the tank, say 1 1/2" onto the bottom at whichever end will be the lowest after installation. Add a reduction bushing and draw your fuel from there. Even better, add a 1 1/2" ball valve, then a longer nipple and a bell reducer. The idea is that any trash and/or water in the tank goes immediately to the outlet where it can be dealt with and the tank contains only clean, dry, fuel. If there is some trash in the tank that plugs the fuel feed line it is a simple matter to close the ball valve and remove the longer nipple to remove the trash. You could put a strainer unit between the ball valve and the bell reducer to make it even more tolerant to trash and more convenient to clean. The more effort you go through to feed your engine clean, water-free fuel, the less often it will stop running involuntarily. Lack of a plentiful supply of clean fuel is the cause of diesel engine stoppage about 90% of the time according to everything I have read. In my own personal experience it has been 100% of the time.

I use this well setup on Bandersnatch to insure any water in the tank gets drawn out before any fuel comes out and have never had a problem due to water in my fuel.

Over the years, as other fuel problems cropped up, I have added more and more refinements to my fuel system to eliminate each problem. Now the fuel goes through a coarse (1/4" holes) strainer in the tank, a fine (bronze window screening) strainer to protect the electric fuel pump (used for priming, fuel transfer, filling filter housing, polishing fuel, testing for leaks and flushing air from the system), a fine mesh screen inside the electric fuel pump, a Racor, and finally the secondary on the engine.

Also be aware, diesel fuel does not like zinc. Galvanize your tank on the outside only, or just use plain steel then sandblast and do a good paint job on the outside.

I would also recommend you look at heavily built plastic tanks. They don't rust, but there is some controversy about their longevity. Be extremely careful about screwing pipe fittings into plastic tanks, the threaded bosses are prone to cracking and once damaged are very hard to repair. Use Teflon tape and do the final tightening with liquid in the tank, tightening only enough to stop the leaking.

From Norm on the IRBS live-aboard mailing list:
Draw fuel from the absolute lowest point in the tank to minimize the amount of permanent sludge carried about in the tank. You want the contaminants in the filters, not in the tank waiting to overwhelm your filters when you have a MOB situation in heavy weather, drop your sails causing your vessel to bounce about and stir up the sludge in the fuel tank, and you really-really-really want your engine to work flawlessly.

A ball valve to shut off the fuel. It would be nice to have valves on *every* opening of the fuel tank, including fill and vent, to seal in the fuel in case of a sinking. It will greatly reduce your problems if the boat is salvageable.

An inline screen about the mesh of window screen, easily cleaned. Mine is a Watts brass fitting, obtainable at a plumbing supply. The original screen was much too fine so I made my own from bronze window screen. This screen is just to protect the electric pump and check valve. You really want the sludge to collect in the Racor. Be aware that Racor has filter elements of several different micron ratings. I use the smallest I can get. It is much easier to change one big Racor filter than several smaller secondary filters.

A clear section (I use a 2" piece of clear fuel hose with a spring inside it to keep it from collapsing) so you can *see* what is being drawn from the tank like trash or air.

An electric impulse type fuel pump (NAPA, Balknap BK.610-1016, red dot, $108) to prime, clean, and troubleshoot the fuel system. This type of pump has a piston and two check valves, just like the old-fashioned well pump, so fuel can be pulled through it [AKA "flow-through"] by the engine fuel pump. A bypass check valve may be required depending on required fuel flow rate when the engine is running.

Compound gauges (plus/minus 15psi) on the input and output of the Racor to see the condition of the filter and another between the secondary (engine mounted) filter and the injection pump to see the condition of the secondary.

I found some nice ones: Gen Svc Liquid-filled, 304SS case, 1.5" dial, 1/8" ips bottom fitting, PN 38545K42, $23.64 ea, McMaster-Carr, 404 346-7000, credit card, UPS.

A crossover valve from the output of the Racor back to the return line to clean your fuel after taking bunkers.

Another valve to draw fuel from the system at the output of the Racor if you want to.

From Norm on The Live-Aboard List:
> Bought bulbs like the ones on an outboard fuel tank line.
> Put them in each fuel line before the primary filter.

You are fooling yourself. The squeeze bulb is a band-aid, a baby step.

A major problem with the squeeze bulb pump is that minor trash can plug up the small clearances in the check valves. If you put a filter upstream between the tank and the bulb to protect the check valves, the bulb will tend to collapse from the suction of the engine pump and the resistance of the filter, with said collapse increasing as the filter collects more and more debris, squeezing the fuel flow down more and more until the engine quits. ...
[I also wonder what might happen to the bulb in case of high heat or fire in the engine compartment. And suppose the bulb flexs constantly as the fuel lift pump sucks fuel through it; would the bulb crack after a while ? I guess you could install valves and hose to bypass the bulb when not using it.]

From Norm on The Live-Aboard List:
I have read that the fuel microorganisms need water in order to live. If this is true, then if you keep water out of your fuel tanks, you will not have a microorganism problem. The key to keeping water out of your fuel tanks is to draw the fuel from the very bottom of the tank. I have wells about the size of a cup in the bottom of my tanks and my suction pipes go the bottom of the wells. By doing this I automatically remove any and all water every time I withdraw fuel from the tank.

Putting the ends of the suction tubes an inch or two above the bottom is a technique left over from the days of professional engineers and day tanks on yachts where the engineer would drain the day tank from a valve on its very bottom to be sure there was no water in it every time he filled it up. Unless you have such a drain valve on your fuel tank, or use the well or similar technique as I do, you *will* accumulate water and associated microorganism glop in your tanks.

A fuel preservative would be a good idea for fuel stored for months at a time, but that is only to protect already clean fuel. You really must keep the water from accumulating in the bottom of your tank.

From article by Steve D'Antonio in 11/2002 issue of Cruising World magazine:
Fuel tank:

From Cruising World's "Find It, Fix It, Maintain It":
When possible, buy your diesel from automotive pumps rather than fuel docks. The turnover is higher, so the fuel is generally much cleaner and it is well worth the trouble of getting it to your boat.

From Jerry Nessenson on Sail World 6/2011:
Ultra low sulfur diesel fuel, now required by the EPA to be sold by virtually all marinas, contains less than 15 parts per million (a 90% reduction) of sulfur and is better for the environment. However, it can cause a multitude of fuel-related problems and requires more than just a biocide that only prevents bacteria.

Ultra low sulfur diesel fuel quickly becomes unstable and contains a high moisture content that leads to corrosion, sludge and plugged fuel filters. More importantly, the sulfur in high sulfur diesel fuel lubricated the fuel injectors and fuel pump. The lack of lubrication can cause expensive premature failure of injectors and fuel pumps unless the ultra low sulfur diesel is treated with a lubricity improver.

From interview of Richard Steinke in Latitude 38:
Mount an electric fuel pump as a backup to the manual transfer pump. It makes priming after a filter change easier, and in an emergency will overcome the effect of a small air leak. It also makes it easier to spot air leaks.

From captkeywest on the Cruising World message board:
... install a vacuum gauge [between primary filter and lift pump] so you can monitor your filter's progressive restriction, avoid unnecessary changes, and most importantly avoid untimely engine shut downs due to a clogged filter. ...

From KC on the Morgan mailing list:
Use the stick method. Pump all the fuel out of the tank that you can thru the normal pickup. You can use a 12 vdc pump from Napa and it will do the trick easy. After you have the tank empty, add fuel a gallon at a time. Either by jug or watch the pump at the dock. and mark the stick as you add fuel. Please do not do this on a Saturday morning. The guy behind you will have a fit as it will take a little time.

Then take the stick and transfer the marking to somewhere on the wall in the engine room. If you or the next owner lose the stick the calibration is still available.

Now for fuel care. Use that little pump inline with your current system, but leave the pump off. The right pump is one that you can blow thru if it is not powered.

Now for the good part. If you have a fuel starvation problem due to whatever, you can turn this pump on and it will draw more fuel thru a clogged filter for a short time. Just what you need sometimes.


From Larry Zeitlinon Great-loop mailing list:
A leaking or broken injector pipe is fairly common. The pipes are subject to high pressure and vibration and any flaw is soon revealed. It is rare that the tubing actually breaks. The usual leakage site is at the joints or compression fittings, probably due to repeated overtightening. If your injector pipe leaked two gallons into the bilge it must have been leaking for several hours.

If you discover a leaking pipe during the middle of the passage, DON'T CRIMP THE PIPE SHUT. This will ruin the expensive injector pump. Rather disconnect the end from the injector, slip a plastic tube over it, and direct the open end into a 2-liter soda bottle. Check the bottle every hour and empty it back into the fuel tank. Then limp home on the remaining cylinders.

From Gene Gruender on The Live-Aboard List:
Re: fuel tank gauge:

Others mentioned the sending units from West Marine. I put one in my tank and the thing I learned is that the manufacturer can't measure tank sizes. They list them as for a certain tank depth, but if you get one, you need one for a tank several inches deeper than what will be listed on the package. I had to take mine back and get the next deeper size, and it still isn't deep enough. I would have gotten the one 2 sizes deeper than the actual tank depth except I had to bend the arm on the second one to get it located before I realized that, even though it was listed as for a tank 3" deeper than mine, it still didn't reach the bottom. Now, when it's about 3/4 full, mine says empty.

Bottom line, don't pay any attention to the sizes mentioned on the package, measure the unit yourself and make sure it will drop down as much as you need.

Fuel senders from wemausa; vertical float instead of one on an arm. Also a model that incorporates an extra fuel draw and return for use with a polishing system.

Filter pore size:
I was surprised to find that the finest fuel filter in my system had 10-micron pores; many people use much finer filters, down to 2-micron pores. But you can't just change from 10 to 2 blithely; you have to be able to get enough fuel flow through the filter, and avoid applying too much suction/vacuum to the fuel pump.

Chris Woodbury's "Nauticat-Fitted Fuel Polishing Systems"
Algae-x Magnetic Fuel Conditioning (some people think this is nonsense)
De-Bug Fuel Decontamination Unit (some people think this is nonsense)
Wil Andrews' "Captn Wil's Diesel Polishing System"
Fuel tank article by Nick Bailey in issue 2000 #1 of DIY Boat Owner magazine
Fuel/water/waste tank articles in Oct 2000 issue of Cruising World magazine
Fuel system article by Steve D'Antonio in July 2001 issue of Cruising World magazine
New to Diesel Engines ?
Jesse Brett's "Fuel Systems Explained"

From RichH on Cruising World message board:
A recirculation polishing system takes advantage of 'turnover' flowrate and a filter that is much coarser than the prefilters found in a normal "in-line" filter set. A coarse filter will have little resistance to flow (GPM/psid) and yet have retention ability down to the sub-micron levels ... but not a very high efficiency of capture. So using a coarse filter with for example a 12v fuel transfer pump (3 gallons per minute @ 1psid) will allow you to 'turn over' the tank volume many times. Each time through, more and more of the very small particulates become trapped until you haave essentially a total background of only submicronic particulate. Coarse filters are cheaper than 'fine' filters. A prime benefit of a high turnover recirculation system is its 'recovery' --- if a huge amount of particulate comes loose from the tank walls, the particle load will 'recover' back to normal due to the high turnover rate --- With a lift pump (at about 2 gallons per HOUR capacity in comparison to a transfer pump at 3 gallons per MINUTE (180 gallons per HOUR) ... the transfer pumps system will turn-over almost 100 times as much fuel in the same time!

I'd disagree with the use of a Racor; they are relatively expensive (huge mark-up for the distributor/reseller) and are more or less designed for 'single pass' filtration. For the filter I'd recommmend a 2.5" diameter by 10 inch long, spun bonded polypropylene microfiber media 15-20 ÁM about $8 in a cheapo carbon steel 'oil-burner' filter ($60). Since such transfer pumps usually come with a protective suction screen, I'd pressure-feed the filter with the transfer pump for the longest in-service life of that filter (vacuum-feed filters are VERY inefficient with respect to 'on-stream or 'service life'). A Walbro model 6802 12v 3 gpm transfer pump is about $150.

From Ed Kelly on The Live-Aboard List:
Re: Epoxy tank coating:

Go very slowly in building Epoxy tanks intended for gasoline.

The formulations of fuels have been changing. What you build for gas in a few years may have other additives in it. By law and in pursuit of profit, fuel is expected to contain more and more Ethanol and other alcohols in the future. Some are destructive of Epoxy. I understand there have been more and more problems of late with tanks failing due to other solvents in the gasoline.

... We earlier talked to the West system epoxy experts and they advised of the problems with some gas formulations ...

Biodiesel and alternative fuels:
Article by Durkee Richards in July/August 2005 issue of Good Old Boat magazine
SoyGold's BioDiesel page
Bob Senter article on SailWorld

Advantages of bio-diesel and bio-/petro-diesel blends:
Disadvantages of bio-diesel:
From Nigel Calder in 2/2008 issue of Sail magazine:
Re: Ethanol in gasoline:

Ethanol, a solvent, will dissolve accumulated dirt in older fuel systems, often resulting in plugged filters and fuel lines. It can also dissolve the resin used in making vertian fiberglass fuel tanks. [It will absorb moisture from the atmosphere, and at saturation point, the waterlogged ethanol will settle to the bottom of the tank and make the engine operate erratically or even stop.]

... install an ethanol-compatible 10-micron water-separating filter. [Expect to have to clean it regularly for a while.] ...

From page on Sail World:
... Yanmar Marine warns boat builders and other customers that biodiesel blends can adversely affect certain metal, rubber and plastic components of engine fuel supply and return systems.

Biodiesel-compatible components must be used instead, so that deterioration and damage do not occur. Builders and/or customers must verify that they are using the correct fuel supply and return system materials, otherwise they will lose their engine warranty protection. ...

From BoatUS article on Sail World about E-15 gasoline:
"... the widely known problems with ethanol's ability to attract water into gasoline, degrade fiberglass gas tank walls to the point of failure, and its solvent-like quality which has led to catastrophic boat engine failures and major repair or replacement costs."

From Glen Tuttle on Sail World:
When we removed the inspection port on the suspect tank, both [2-year-old] Buna-N gaskets were totally disintegrated, and chunks of them had stopped up the fuel ports. We checked on the other tank and same thing happened, but to a lesser degree as those gaskets were only about a year old.

An hour of Internet research revealed:
All known gaskets, seals, hoses and O-rings are compatible with blends of less than 20% biodiesel. For higher BioheatR fuel Blends than 20% biodiesel, up to and including 100% biodiesel, compatibility will depend on the materials they are made from. For BioheatR fuel Blend concentrations over 20% biodiesel, fluorinated polyethylene, fluorinated polypropylene, Teflon, Teflon lined, or Viton Components are recommended. Use of other types of materials in BioheatR fuel Blends over 20% biodiesel such as nitrile, natural rubber, or Buna-N type rubbers may cause leaks, plugged filters (due to dissolved material) and eventually complete gasket, seal, hose or O-ring failure.

Lauren Dunn's "US Body issues damning verdict on E15" on Sail World

From George Adams on MadSci:
Re: Can gasoline be used in a diesel engine ?

Gasoline and diesel fuel are very similar. Gasoline is the portion of crude oil that boils between about 100 and 400 degrees F. Diesel fuel is the portion of crude oil that boils between about 400 and 600 degrees F. However, an ordinary diesel engine will not run on gasoline, and a gasoline engine will not run on diesel fuel.

A gasoline engine works by compressing a mixture of gasoline vapors and air in a cylinder and igniting it with a spark, driving the piston and creating the power. A diesel engine works by compressing air in a cylinder and injecting a liquid fuel into the cylinder. The air must be compressed to a high enough pressure (much higher than a gasoline engine's pressure) that it will be hot enough to ignite the fuel without a spark.

If you try to run a gasoline engine on diesel fuel, the fuel will not be vaporized satisfactorily, and if it ran at all it would be sluggish and would exhaust a cloud of smoke. If you try to run a diesel engine on gasoline, the gasoline will vaporize and ignite prematurely and the engine will sputter and knock and eventually stall. (I know this from experience because I once rented a car that I did not know had a diesel engine and I filled the tank with gasoline.)

Kerosene and jet fuel are portions of crude oil that are similar to diesel except that they usually will not contain the highest boiling part. They should work in a diesel engine, but not in a gasoline engine.
Gasoline in a diesel engine: I think mistimed ignition could break piston connecting rods or damage crankshaft bearings and destroy the engine. And gasoline lubricates less than diesel fuel, so you might wear down cylinder walls or the fuel injection pump. And alcohol in gasoline might affect fuel system gaskets and hoses. And unburnt gasoline could ignite inside the exhaust system. But I do know someone who mixed about 4% oil into gasoline and ran a diesel engine on it for several hours to get into port.

Bookmark and Share

Site Map     

Privacy policy