Fuel bugs

As we describe in Dirona fuel manifold, we choose to explicitly pump fuel from the appropriate bulk tank to the supply tank rather than gravity feed. This is a slightly more manual operating mode but has some advantages that we really like. The first advantage is that a leak in the supply system can put no more than 62 gallons in the supply tank at risk, keeping the up to 1,747 gallons in the side tanks safe. A supply system fuel leak when gravity feeding can drop the entire bulk fuel load, risking environmental damage via a large fuel spill in addition to being out of fuel. Avoiding this is important any time, but especially when doing long ocean crossings sometimes more than a thousand miles from the closest shore. Having no fuel when days from shore could really be a disappointment.

The second advantage of the explicit fuel transfer system is all fuel has to pass through the transfer filter before it reaches the supply tank. Given the uncertainty of fuel quality world-wide, we really like a layer of filtering prior to the fuel even entering the supply tank. The combination of keeping the bulk fuel locked up and safe from leaks and the additional layer of filtering makes this operating mode important to us. It is a bit more manual work but it feels worth it. This is the source of the first fuel system modification we made. The standard fuel pump, a Walbro 6802, is incredibly slow at 43 gallons per hour. In fact, so slow that this way of operating the boat can be frustrating. So we replaced it with a Jabsco VR050-1122 pump capable of 660 gallons per hour. And with our restrictions and filtration it moves around 205 gallons per hour.

Like many modifications, when you make one change, it can drive others. To accommodate the transfer rate of this pump, we needed to go with a much larger transfer filter. We went with a Racor FBO-10, which is commonly used in bulk pumping and aircraft fueling applications. This filter has the advantage of supporting large transfer rates but it also has a large filtration area so few filter changes are needed. This is a good thing, as the filters cost about $100 each. Changing this filter is bit of work, as it holds a lot of fuel that must first be drained off. But we really like the filter because of its massive surface are and durable build. The FBO-10 can operate for long periods of time through heavy debris, sand, water, or even bugs. The filter below took us all the way across the South Pacific, the Indian Ocean, and the Atlantic Ocean.



You often hear boat owners complaining of “fuel bugs” but what they are really referring to is the layer of biological growth that can occur at the interface between fuel and any water in the bottom of the tank. The dead matter that falls out from this nasty stuff can really plug filters, This can get particularly bad after the addition of a biocide causes mass death or when operating in rough water and the layer of sludge left behind gets stirred up. Although fuel bugs is not a technically correct term, you will hear it frequently. So I laughed when I found our FBO-10 had captured a real bug. Apparently a cockroach met its end in a fuel storage tank prior to being delivered to Dirona and our filter actually was blocking bugs.

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39 comments on “Fuel bugs
  1. Michel Sirois says:

    Hi James,
    Hi just bought the same pump. Getting ready to install. Wondering if you had to change hoses and fittings. My N50, for the tranfer circuit is mounted with dash 6 hoses and fittings. What does this size and restriction do to the pump? Any other alternative for filter which would be less of an overkill? Port size are huge on the Racor FBO filter.

    • It’s a great pump and, yes, you are right that gear pumps are positive displacment pumps and can only deal with a bounded amount of back pressure before they over-load. We also have SAE-6 fittings and hoses and the resistance to flow in the system various by length of the run, number of fittings, and the return to our supply tank has a pipe that runs to the bottom of the tank which adds some additional restriction. This pipe to teh bottom prevents splashing noise when at a quiet anchorage when the diesel furnace is running. In these conditions, it’s dead quiet outside and the engine isn’t running so the sound of the fuel recirculated by the diesel furnace was annoying.

      As a consequence of so many different restriction levels in the fuel system, we put a bypass on fuel transfer pump. This valve connects pump output to input. We have a pressure guage on the pump output and just adjust the valve to 10 PSI positive presure. It works well and delivers a precise quantity of fuel. At 10 PSI, we flow 3.4 gpm or around 204 gph which is still a bit more than 2x the max flow rate of RACOR 900s.

      We really like the FBO10 because it has huge possible flow rates and lots of surface area so it’s just about impossible to find fuel of poor enough quality to require an early filter change. But, you are right, it’s more than is absolutely needed for the application. As the first fuel filter that sees all fuel flowing to the supply tank, we like having a monster but certainly smaller systems would work fine. Tony Athens of Seaboard Marine makes some very nice filtration systems many of which are more compact than an FBO10.

      • Michel Sirois says:

        James, thanks for that great info.
        I will go for the bypass, valve and pressure gauge idea too. Did you go for SAE 6 fittings and hoses for the bypass as well?
        Do you think if operated at slightly less than 10 psi, so less flow thru filter, I could be OK with a Racor 1000. They are rated at 180 GPH. My other option is a Fleetguard FS1218 which appparently are rated at 250 GPH but i have seen conflicting specs. I know they are not necessarly the best and only way to go, but for different reasons I like Racor filters cause they are found anywhere, are cheap and I like seeing the colour of my fuel. Nothing scientific or hard based behind that, lol.
        Sorry for the delay in responding to your reply. We are on the move theses days, and not always well connected.
        Glad you guys seemed to enjoyed the east coast NS. I am from NB and has sailed extensively the Maritime provinces and the coast of Maine.

        • Yes, we are enjoying the east coast of Canada, Maine, and New Hampshire so we haven’t been moving south very fast. However, we woke up this morning to 38F so it may be time to pick the pace up a bit. They do have winters up here and it is obviously approaching.

          If you are careful and watch the pressures, the design you describe should work fine. We did use -6 fittings for everything. Most are SAE but there are some JIC on board. I believe Nordhavn builds the fuel system with all SAE fittings.

  2. James I thought of another question for you concerning fuel use on Dirona.

    Since you transfer from your bulk tanks into the supply (Day) tank, I assume you return unused fuel to the supply tank.

    I’ve been reading multiple blogs with cascade failures on different systems due to heat and got to wondering about fuel temperature on Dirona.

    If I remember correctly you can expect a 1% decrease in horsepower for every 10 degrees Farenheight above 90 degrees F with #2 fuel oil.

    With your long run experience I would imagine you’ve seen some rather high temperatures in the engine room. I was wondering if you saw any effect or if the supply tank was small enough to run through the fuel before heat became an issue?.

    • Great topic Steve. Certainly one where I have given considerable thought mostly because every solution either brings more problems and more costs and many are interrelated. There are many different decisions you could make along the way but here’s the thinking behind ours:

      1) We prefer to not gravity feed fuel into the supply tank for two primary reasons. First, if a leak develops in the fuel systems, you could easily lose the fuel load when gravity feeding. When not gravity feeding, the only fuel that would be lost is the supply tank. I don’t like even the low probability event of being 1,000 nm off shore with no fuel left. The second reason we prefer not to gravity feed is covered by this article: it’s good to have a large industrial filter to rocks and small birds (as Bob Senter has been known to say). You can see from the pictures how much debris didn’t make it to our supply tank. For us it is worth it. So every 4 hours when we do an engine room check, we pump a new load of fuel into the supply tank.

      This decision ensure all fuel gets filtered prior to the supply tank and prevents the entire fuel load from being at risk if a leak develops. But, it brings the problme of increased fuel temperature so one improvement brings another problem to mitigate.

      2) The fuel temperature problem is increasing temperature in the supply tank on longer runs. Using the desing above, the tank will eventually stabilize at 140F when it’s filled and can creap as high as 180F when very low. And, this won’t take long. The fuel leaving the cylinder head will be existing at 160 to over 185F on our engine. So, the less fuel in the tank, the higher the temperature and, when using the small supply tank, it doesn’t take long to get quite warm. In fact, on very long runs, the fuel temperature problem is a problem no matter what system you use if the tank levels start to get low.

      For more than a year, we just put up with the fuel temperature problem because we liked the upside of using the supply tank as a source and return for fuel and, technically, John Deere specs allow continuous operation with up to 212F diesel. So, technically it is fine. Steve, you mentioned that at higher fuel temperatures engine output decreases and the decrease can be fairly large. It is true that the max engine output will be reduced by higher temperature fuel but modern engines measure air and fuel temperature and compute the appropriate masses so mixtures stay correct at all fuel and air temperatures. But, it is true that max rated output will be less at higher fuel temperatures. Generally, when running long distances an engine is never close to max rated output so this is really not noticable and not an issue.

      The loss of power is not consdequential and the fuel return temperature is always less than the maximum specified by John Deere so, on the face of it, this becomes a non-problem. But I really don’t like the super high fuel temperatures even if Deere is fine with them. Competitors like Cummins specify a far lower max fuel temperatures and, the more I think about it, the more I’m convinced that lower temperatures fuel yeilds better lubrication and the only lubrication fuel system parts get is the fuel itself. With the common rail pressure up over 18,000 PSI (1200 bar), good lubrication becomes important. It’s this last issue that eventually convinced me to install a fuel cooler. I just don’t think that 160F and above fuel is good for the fuel system.

      At this point we have the fuel supply safe from leaks, we have all the fuel filtered prior to the supply tannk, and we have the engine running on diesel that runs a nice cool and stable 100F to 110F. Life seems pretty good but there is now a new risk. What if the fuel cooler leaks?

      3) Mitigating leak risk. The fuel cooler is a liquid to liquid heat exchanger where salt water is teh coolant and fuel is what is being cooled. If the fuel cooler leaks water can end up in the fuel on the way to the engine. There are two filters on the engine but it’ll become a race between how fast the engine can detect and alarm on water and wether some makes it past the filters. If it does, the injectors will likely get blown apart by super heated steam the high pressure pump may be damaged. Essentially this outcome is worse that the outcome if running on hot fuel so this is a show stopper.

      The mitigations we used to reduce the probability of this nasty outcome to very low levels are first to put the cooler in the return line. Any leaks where water finds it’s way into the fuel will first flow back to the supply tank which has a sump that will collect water (fuel is pumped off 4″ above the bottom) and the sump has a water in fuel sensor that will alarm in the pilot house. And, there are 3 more filters between the supply tank and the main engine. This takes the downside risk down very low. We further reduce it by using a very high quality cupronickle heat exchanger that is used in industrial applications moving very nasty fluids.

      At this point we have cool fuel which we believe is better for the fuel systems, we have a sysetm that won’t lose the entire fuel load on leak, we have a system that filters all fuel before the supply tank, and we have a design that is very unlikely to have a problem with water leaking into the fuel system. But, like many engineering projects, each “improvement” brought a new problem and it takes care and careful thought to mitigate the entire system of risks and get a good design.

      • Steve Coleman says:

        Very cool James (I mean that literally),

        In case the fuel cooler does leak and you start seeing water in the supply tank sump do you carry a spare cooler or just have the necessary parts to bypass it until you can get to port?

        I would really like to see a picture of the fuel cooler installation if you ever get the time.

        • Yes, there are two issues I forgot to have in the long list: 1) if the cooler leaks, you need a fast access bypass, and 2) when operating in artic conditions, the cooler could actually over-cool. The mitigation to both is a value actuated bypass.

          This brings up yet another potential risk, if the bypass handles are accidentally set incorrectly they could put a resistence in the return fuel flow. On many engines, return fuel flow blockage is an expensive mistake.

          My approach to first two issues is a permanent bypass. My approach to the third, is to wire tie the handles into the correct position so the only way to make a mistake is to first cut the wire ties and make the change. This is a picture of the finished product:


      • Brian Smith says:


        I happen to have an unused raw water inlet that would be great for cooling fuel before it returns to the tank. Instead of my researching the heck out of cupro-nickel heat exchangers, I’ll just ask you – which one did you buy?

        Great to hear about Jennifer’s progress!

        • We used a Hydac #3784062 that we purchased through Gateway Hydraulics. Hydac is at http://www.hydac.com and Gateway is at http://www.gh.com.au/. I believe that Hydac is a German company and Gateway is in Gold Coast Australia (but happy to sell to customers anywhere).

          If you are ever in Australia, Gateway is one of the best. Bob McCallum who leads Gateway is an unusually creative engineer and close to unstopable when faced with a problem.

          If you are choose to source an exchanger locally, what we used is a copronicle braised plate heat exchanger.

          • Brian Smith says:

            Thanks, James. Google can’t find that particular part number, but I’ve got an inquiry into the FL Hydac distributor to see what they can turn up. Appreciate it!

            • The label has a part number and a type. The part number is #3784062 and the Hydac type is “HEXS610-11-INO825-N1/G1”. I’m reading from a picture since it’s hard to get to. The part number is super clear but the last 4 characters are hard to call on the type. Hopefully that is enough for your contact at Hydac.

              • Brian Smith says:

                They have apparently dropped that part number, but still have models of the HEXS600 that are very similar. Would you say yours is about 1 1/3″ thick, or more like 2 1/4″ thick? (The former is their current 10-plate model, the latter is their current 20-plate model.) From your photo, it looks a lot more like 1 1/3″ than 2 1/4″, would you agree? Thanks so much!

                • Brian Smith says:

                  Sorry, one more question – what pump are you using to pump the raw water through the cooler? I don’t see that mentioned anywhere. Thanks.

                  • I’m using the the hydraulic heat exchanger water flow. The heat exchanger is first and the only time the hydraulic systems runs hotter than engine room ambiant is when the windlass or thrusters are in use. Stabilizers only run at 1,500 PSI and loads are fairly low. This saves me from having to run yet another water pump.

                    • Brian Smith says:

                      You say “the heat exchanger is first” – but which one? The hydraulic heat exchanger, or the fuel heat exchanger? (I’m going to assume the hydraulic heat exchanger is first – since it was already there, someone obviously felt it was more important than a fuel chiller. Yes?)

                    • Yes, exactly Brian. The hydraulic heat exchanger is first. I don’t want the hydraulic system ever up over 150F. It alarms at 160F and shuts down at 180F. In this config the fuel never gets up over ER temps — it’s working pretty well.

                • Yes, exactly. It’s the thinner of those two coolers sizes.

  3. Dan Martin says:

    That’s the first legitimate fuel bug I’ve seen!

    You might want to look into converting to Caterpillar fuel filters made by AFSI. http://www.afsifilters.com/

    Exxon Mobil uses Cat filters in their lab for assessing fuel and oil cleanliness. They’re about the best quality you can find and much more affordable than those Parker filters due to the volume produced for Cat machines. You can also get them just about anywhere in the world, which might be handy on your travels.

    Love your blog!


    • That’s a good point Dan and I should have thought of it since we have so many Cat generators at work. I’ll not change now that I have a working system but, were I to do it again, I would follow your advice. Thanks for passing it along.

      • Dan Martin says:

        I think you’ve got a great setup already, so I wouldn’t change any hardware. I use a Cat filter on my Generac genset, so there might be a 1:1 replacement cartridge for the filter you use now. Something to look into the next time you’re shopping for a replacement.

        All the best,


  4. John Maguire says:

    Amen to Over Engineering!
    I have quite the array of pumps and filtering(re-filtering and filtering again) systems in my world and I have to say when the time comes I will spec seal-less pumps and god I love my bag style filters…..never a bit of residue in my housings is reason enough…I installed a smaller dual lead-lag assembly on my bus..25 up front and 5 polishing that feeds into a Racor 900…nothing gets to the Racor let alone my engine…filters store super easy, change out is painless and they are dirt cheap. I pumped some acids and after trying everything I went with some seal-less pumps and changed all of my pumps over, mine are larger Teikoku can units and one small Imo, but I haven’t touched them in an age now where they were a regular failure item. I think the reduction in any sort leaking possibilities around a reciprocating shaft is a huge bonus and the design is just awesome. I am not familiar with specific regulations but I am sure various marine applications must exist with both the pumps and the filters. One other addition I might make if I were getting fuel from all sorts of locations is a Vaisala MMT330 water in oil sensor…I actually bought several of these off eBay in the box for $600…it measures water content below the saturation point. You could pop one in the incoming fuel stream and set a barrier limit and alarm that if exceeded would notify you of excessive water content….very cool device.

    • I’m familiar with mag drive pumps and have used them in aquarium applications but the Teikoku canned pump design looks even better. Same approach as used on most air conditioning compressors. Nice design.

      I like the idea of measuring the water entrained in the diesel but I’m not sure what I would do with the data since in most places where we have fueled in the last 6 months, there really were no options or alternatives. Surprisingly, in 17 years of boating, we have only had material water in the fuel twice. Once up in Northern British Columbia and once in the original fuel load that came with our current boat. Both filtered out fairly quickly and easily. We of course have water in fuel sensors at the bottom of the supply tank and on the first level on-engine filter and I check for water on the other filters. But, it’s not been a problem in recent years. I’ve seen rust and debris but no water.

    • Matt Baker says:

      Awesome post James… My favorite non-IT blog on the web. John M. comment on “over engineering” made me giggle a bit given your recent Patterson post praising the notion of “replacing an incredibly expensive “enterprise quality” component(s) with a set of redundant and less expensive components just keeps playing out”…except in Nordhavn fuel systems :)

      • Interesting observation Matt. Arguably, we are using some of the principal on the Dirona Fuel system. Rather than replacing expensive on-engine filtration, we agressively filter at the Racor 900 where we have $13 filters and can switch between the two installed. It’s not quite redundant since only 1 filter is in use at a time but they are cheap, high volume parts. The FBO-10 is admittedly leaning towards gold plated rather than commodity :-).

  5. Hello James,

    First I have to say I love reading your blog. I doubt if more than a couple of days go by that doesn’t find me checking for another post since I first stumbled over it.

    I hope Jennifer heals quickly allowing you two to continue with your travels thus giving me additional material to ponder.

    My reason for posting however is I’m somewhat confused on why your chose a RACOR FBO series filter rather than a SFBO?

    I’m probably wrong since I’m a dirt dweller, and have been since 1979 when my tour of duty ended, but I didn’t think the FBO-10 was approved for marine use inside an engine room.

    It was just something that peaked my interest and I’ve been unable to satisfy it using Google.

    Keep up the good work, I hope to be reading about you two for years to come.

    • Thanks Steve. You were asking why we didn’t install an SFBO-10 rather than an FBO-10. The short answer is the SFBO was not available at the time. There were only FBOs being installed back in 2009 when this one went in.

      The SFBO is a relatively new release to meet some international regulations for marine engine rooms likely related to long term fire resitance. The SFBO doesn’t have much online data on it at this point and it’s hard to find much data on what is different. It looks identical. I have seen manufacturers charge more for getting a part certified even though the certified part was identical other than being painted white. The only way to know the difference deffinitively is to ask Parker or find the parts list in each. I’m guessing the regulations might be European only since the only data I found was from Parker EU. Thanks for pointing out the SFBO as an option.

      • That makes sense James, really the only difference I saw in your FBO and the SFBO’s I researched was construction material. The SFBO used a cast iron top and a steel bowl.

        Even though I’m a dirt dweller, I do work with steam or hot water comfort and process boilers which many use diesel or oil.

        While I personally prefer iron and steel, I cannot think of a situation where the materials would make that much of a difference to you.

        Your installation is protected from accidental physical damage (what are the odds it’s going to be rubbed by lets say a fork lift?), and quite frankly an engine room fire that would rely on the difference between aluminum and steel is already beyond catastrophic.

        I did think of another question, are your filters rated at 10 Micron Nominal, or Absolute? I was thinking while looking at the filter and bowl pictures if you got a year out of a Nominal rating your tanks are relatively clean.

        If they are Absolute, I’d consider them almost pristine.

        • Hey Steve, thanks for the additional detail on the Racor FBO-10s. The FBO-10 from the 2009 vintage actually does have a steel bowl and cast iron mounting plate. Perhaps what I have is now what is sold as SFBO-10 and the FBO has gone to a different material? The one installed on Dirona is a steel bowl and a cast iron top.

          The FBO filters don’t appear to document whether they are 25 micron nominal or absolute so I’m not sure on that one. The we operate our boat the FBO-10 sees all fuel that goes to the supply or wing tanks and we only consume fuel from the supply or wing tanks. The wing and gen have 2 filters after the fuel tanks and the main has 3 so all fuel that goes to the main will see 4 filters. And, since modern diesel recirculate so much fuel, the average unit of fuel will have passed through the FBO-10s once and then through the other 3 filters many times.

          • It could very well be that the old FBO’s were iron and steel the specs I looked at were for current models only. Either way it sounds like you are covered and had I realized that, I’d have simply stayed lurking in the background.

            It really doesn’t matter with what I read about the fuel system on Dirona because as you say you’ve got multiple filters, I only asked the rating since I was trying to determine how clean your tanks were from a guess of filter and bowl conditions. Even with a 25 Micron (I thought I had read 10 somewhere) it looks pretty clean to me.

            If the filters aren’t marked, it means they are Nominal. Nominal ratings are what I would use for anything with multiple filters like you’ve got anyway.

            Thank you for taking the time to respond to my questions. I enjoy reading about your approach to modifications and maintenance, this article simply peaked interest in something I couldn’t answer on my own.

            • I appreciate your comments and learn from them Steve.

              We have an unusual configuration that runs counter to most expert advice of running increasingly fine filtration from the pump to injector. What we do is run 25 micron in the FBO-10, then a 2 micron in a RACOR 900, then 10 micron on engine and finally a 2 micron on-engine. We document the thinkking behind this unusual design at: //mvdirona.com/2013/12/dirona-fuel-manifold/.

              That article shows pictures of the filters and manifolds but the short summary of why we run 2 microns in the primary filtration position is we can change these filters whithout shutting down the engine and they only cost $13 rather than $140 for the on-engine filter. The downside of this approach is you can use more filters but the 25 micron in front stops the big stuff and we do have more than 40 of the 2 micron filters on the boat :-).

              • Well James, I’m not by any means an expert in anything or even a engineer. I do however from time to time have to figure out why something a engineer has specified doesn’t work as well in the field as it should on paper.

                For your purposes, I see nothing wrong with your system as I understand it from your descriptions. The best test is it’s working, since I can’t remember ever reading of an instance where you had problems with fuel.

                I am however going to throw something out there for you to consider.

                Since your replacement cartridge for your FBO-10 is not marked, it’s probably a Nominal filter. That means 50% of anything 25 microns in size is trapped at that point.

                We then come to the RACOR 900 and from the cost of those cartridges I’ll bet they too are Nominal. That means 50% of anything 2 microns in size are trapped at that point. No real worries there since we are down to the size of bacteria.

                Next comes the 10 and 2 micron filters on the engine. From your cost description of $140.00 even if it’s for both they are quite possibly Absolute. That means they are specified to trap 98% (actually 98.7% if I remember correctly) of the particles 10 and 2 microns in size.

                Where I am going with this is, your 10 micron filter is probably not doing much for you other than some ability to trap a limited amount of moisture. Unless you haven’t been paying attention, that shouldn’t be a problem after the FB0-10 and RACOR 900.

                If it was my system (which obviously it’s not) I would consider replacing at least the 10 micron filter with a 2 micron Nominal leaving the final 2 micron Absolute in place. I might even consider replacing them both to Nominal filters. How unlucky do you have to be for something 2 microns in size to get past 3 filters? Would it make any difference? To me it wouldn’t, but then I’m not dealing with diesel engines.

                Assuming (we all know what happens there) you are buying John Deere filters, I’d also research whether they were actually rated at Absolute or if I was simply paying for the branded name. John Deere doesn’t make those filters, someone like FRAM or WIX makes them and brands them accordingly.

                Another consideration is if the media begins to plug with a spin on filter it simply goes into bypass. I’d rather have a Nominal filter I could afford to change more often than an Absolute which could bypass without me knowing it.

                Just something for you to think about when you have time.

                • As an example I could by a 3 micron absolute $25 oil filter from Harley Davidson for our bikes, but choose to buy a 3 micron absolute from WIX for $4.75.

                  • Thanks for your last two posts on filtration Steve. You are 100% right that Deere does not make the on engine filtration. But, since the fuel system on common rail systems are incredibly sensitive to even small amounts of dirt, water, or other impurities, I’m not crazy about changing the filter ratings. My thinking is I want EXACTLY what Deere speced. In fact, I’m not crazy about changing anything about the fuel system knowing that Deere tested the filters they speced but almost certainly nothing else.

                    That’s why I use Deere 10 micron followed by a Deere 2 micron even though I have finer filters earlier in the system. I basically don’t want to change anything after the on-engine low pressure pump. However, your point remains that Deere OEM these filters and I probably could get exactly the same filter from their supplier. That investigation is on my list. The two Deere on engine filters are part of an assembly made by Racor that includes the variable speed low pressure pump. Since this system is made by Racor and sold to other manufacturers, I almost certainly could source these parts less expensively elsewhere.

                    Where that leaves me is I’m not willing to run other than 10 micron followed by 2 micron for the Deere on engine filter. And I’m not even willing to go to a second source for that filter. But, since it is a Racor part I would be willing to replace it with the same part obtained from another source. The only reason I haven’t so far is the filters are protected by such agressive filtration ahead of the two on engine filters that they never plug up and I just replace them on time duration.

                    The reason why my first level filtration is 25 micron is I’m after getting the big stuff out so the 2 micron that is next in line is not working as hard. And, since the Racor 900 2 micron filter is only $13 whereas the Racor FBO-10 25 micron is nearly $100, I prefer replacing the former if I have a choice.

                    I will eventually do the research to get the two on engine filters from a cheaper source than Deere but I will continue to go with the same source (Racor) and the same filter ratings only because I’m loath to change anything in the Deere fuel system given how mission critical the system is on our boat. And, our on-engine filtration budget it pretty tiny so there isn’t much motivation to go lookking for further savings.

                    Thanks for suggesting sourcing the on-engine filters directly from the manufacturer rather than Deere. We will likely do that.

  6. Chasm says:

    Nice example of a system that just works.
    Just looking at the headline and the last picture without reading I thought you were a day late. ;)

    • I love over engineered solutions and the FBO-10 is overkill for this application. It’s normal use is high output comercial pumps and it deals well with very high level of debris. We certainly could have changed it earlier but, what we do is have vacume guages on all filters. Experts advice to never go longer than a year and we don’t on the cheap and not particularily durable RACOR 900 filters. The reason why experts recommend replacing at least annually is water can break down the filter media. My read of the FBO-10 media is it is far tougher than most other filters we use so we are happy to run them longer. There are also 3 more filters before you reach the main engine :-).

      Even with all the debris in the pictures, the vacume guage still showed no measurable blockage. The FBO-10 is a beast.

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