Dirty Diesel Done Cheap

In early December we crossed the Sea of Cortez from San Carlos/Guaymas to Bahia Concepción. Finally, we were away from the boatyard and all the tasks that come with getting a boat ready to launch.

After some initial uncomfortable beam seas, Melissa and I enjoyed a fairly pleasant crossing with light winds. We had the headsail out and the engine running, making perhaps six knots. Evening was fast approaching and we knew that we would be anchoring at night. No one likes to anchor in the dark but we had anchored in Bahia Santo Domingo a few times before and we had our GPS tracks to follow and permit safe entry into the bay.

A few miles out from Punta Concepción The engine slowed to an idle and then just died. I furrowed my brow. Melissa looked at me, waiting for an explanation or at least some calm assurance that this was perfectly normal behavior.

“WE’RE ALL GOING TO DIE!” I shouted, pulling at my hair. I may have wet myself a little.

No, I did not do that.

Melissa and I swung into action taking the roles we have perfected over years of sadly similar mishaps. I furrow my brow, concoct an uninformed theory on what just happened and then go below to figure things out. Meanwhile, Melissa works out a strategy to keep the boat safe or keep us moving in the direction we wanted to go. That is how we have handled all previous crises. Just check out Badda-Bing-Badda-Boom or How I Spent My Summer Vacation for more examples.


Fuel Filter System

The fuel filter system I installed on Galapagos almost five years ago. The two filters and the fuel valve below them allows me to change filters quickly if one becomes clogged. An electric fuel pump, lower left, pulls fuel from the tank.

So, my ill informed theory on why the engine died was that the fuel filter was clogged with some algae that had blossomed in our fuel tank during the hot Mexican summer in the boat yard. Common wisdom has it that you should keep your diesel fuel tanks full when placing your boat in storage. This prevents water from condensing in the tanks as the hot, humid air cools in the evening. This moisture collects at the bottom of the tank and forms a warm and inviting location for a kind of algae that loves to munch on diesel fuel. Fuel systems that are heavily infected by “the bug” can quickly clog their filters, especially if that fuel is agitated by bouncy seas or heavy weather. I only had my tanks half full when we put Galapagos away back in June and I secretly worried that this might give me grief at some point.

Theory in hand, I went below and switched the primary filter from number two to number one. I looked at the bowls of both filters and did not see any water but I was troubled by a little sediment that had settled at the bottom of the bowls. Had we been infected by the dreaded bug?

I asked Melissa to try the engine and it started right up. Theory validated! I explained my concerns to Melissa. We would have to keep an eye on the filters but we could proceed to our anchorage safely.

Control Box

This little box allowed me to install a small relay to run the electric fuel pump when the ignition switch is turned on. I also installed a manual switch to run the pump in the engine room when I am replacing the filters. The switch in the lower center part of the box is for the Balmar Alternator.

After about ten minutes, my brow was slowly unfurrowing when the engine died a second time. My theory was starting to unravel; The second filter couldn’t be that clogged that quickly, could it? And something else was bothering me. Something was missing when I had been down in the engine room but I couldn’t figure out what it was. Some noise… a clicking sound.

With the boat quiet, I went below again. When I had installed the engine, I added an electric fuel pump to pull fuel up from the tanks. Diesel engines are fitted with small mechanical pumps but if the engine is too far above the fuel tank a small electric pump is used to provide additional pressure. This little pump runs whenever the ignition switch is turned on and its familiar little clicking noise was what I was missing.

In a few moments, I found the problem. A connector inside my little control box had worked its way loose. A minute after fixing this issue, we restarted the engine again and were on our way. As we lay at anchor later that evening, I reflected on the pleasure of knowing Galapagos so well that we can hear and feel when things are working well and when something is amiss. Having installed, replaced or at least touched every part of this boat, Melissa and I have a lot of confidence in our abilities to keep her running smoothly.

But visions of algae kept clogging my brain. The fuel filters weren’t dirty yet, but maybe I should have a look in my tank. How old were those filters anyway? Four, five years?  They had about 500 hours of run time on them which meant they should be replaced. Pretty soon, I had worked my self into frenzy, certain that if we didn’t act soon, the engine could quit at any moment and maybe even be damaged because I was too lazy to check my fuel.


Melissa documents the process with her Iphone. Some people post pictures of their lunch, or cute cats. We post pictures of hydrocarbon eating algae.

And so once we were settled in La Paz, Melissa and I began to explore the wonders of our diesel fuel tank. Since, as usual, we didn’t know what the hell we were doing, we took an incremental approach. I used a small pump that attaches to our ever handy Ryobi cordless drill and pulled a sample of fuel from a hole located on our inspection port. Looking back, I think all this sampling and filtering was mostly an excuse to delay the inevitable. It certainly gave me time to accept my fate and think about how to pull 40 gallons of dirty diesel from the tanks with as little drama as possible.

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Pulled a small sample of fuel before we went too crazy; just to see if there was crud in the tank. Spoiler alert: there was crud in the tank.

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Michael examines the fuel sample in his laboratory.

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We used a coffee filter to filter out the debris. At this stage we were still in denial about how dirty the tank really was.

With proof in our jar that there was stuff floating around in the fuel, we began to think of how to clean this fuel. At this point, we did not have enough containers to suck the fuel out and store it elsewhere so we could have good look at the bottom and walls of the tank. So we just used our hand drill pump and Baja filter and drained the freshly filtered fuel back into the tank. We did this for a couple of hours and the stuff we saw captured by our filter would curl your injectors.

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If you don’t like the smell of diesel, stay out of the kitchen. The access plate to our tank is right in front of the galley sink. That means just about all other boat activities stop while we attend to the fuel. The metal cylinder is called a Baja filter and it contains three screens which provide progressively finer filtration.


What is this stuff

Very shortly after beginning to filter our fuel, we sucked up this thing. Sure looks like pond scum to me. The white piece looks like silicone sealant of some sort. After seeing this, we knew we had to empty and clean the tank.

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We were getting so much debris from from filtering the fuel that our Baja filters were clogging up quickly. Melissa had some No-See-Um netting that we used as the first filter. This netting is finer than mosquito netting and worked great.

After this initial effort of filtering fuel back into the tank, We were now solidly convinced that a more comprehensive cleaning would need to take place. That meant fuel storage and so our search for inexpensive fuel containers began. Just like the good ol’ U.S. of A, if you put the word “Marine” or “Boat” on a product in Mexico, it is magically much more valuable and therefore expensive. Fuel cans at the nearby chandleries were about 800 pesos (40 USD) each We needed six containers. You can guess that we took a pass on spending 240 dollars on this project, however nice these fuel cans might be.

Instead we went to the Home Depot in two trips and bought six 20 litre fuel cans for 71 pesos (3.50 USD) each. Now it is true that these cans are not as rugged as the nice containers at Lopez Marine. They are also not yellow and I really wanted yellow because everyone knows that yellow cans are for diesel. And we had to schlep These cans back on a collectivo while being warily eyed by concerned Mexican ladies. But at 71 pesos each, I am willing to flaunt social nicieties and use red instead of yellow. We sold half of these containers after this project.

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Our Collection of fuel cans used to hold the diesel we pulled from the tanks. The dark red cans we bought from Home Depot here in La Paz for this purpose. With all of our cans and buckets, we had 40 gallons of storage available. After the tank was as clean as we could make it, We used our Baja filter and a fuel siphon to pour the fuel back into the tank. In this way, the fuel got filtered twice.

As we filled container after container with diesel, we could begin to see the bottom of the tank. I used a scotch bright pad to scrub the bottom and sides while there was still some fuel in the tank to loosen any reachable grunge and then pump it out. While we were getting some solids during the whole process, we never saw the horrifying clumps of goo like we did at the beginning of this project. I should also add that I had added Star Tron Tank cleaner to the fuel and let it slosh around in there for a day or so to help loosen the crud from the the tank walls. I have been using the Star Tron Enzyme Fuel Treatemnet on Galapagos since we bought her.

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Michael trying to look for bits of grunge to wipe up. We were both stiff from being crouched over this hole for hours.

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After emptying most of the fuel from the tank, we could finally see this little sump area where the dip tube stands. This part was very difficult access and we were disappointed that we couldn’t clean it as well as other parts of the tank.

Using a length of Pex tubing left over from re-plumbing the boat, I was able to reach most of the tank’s corners where debris likes to collect and suck it up.

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Here you can see the baffle inside the tank and the blue tubing I used as part of our vacuuming system.

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The walls of the baffle look grungy but wiping with a rag did not yield much dirt. You can never achieve perfection with a project like this.

After pulling 40 gallons of fuel out of the tank and cleaning it as best we could, we were ready to put the fuel back in the tank. Using our Baja filter again, we siphoned the fuel from our fuel cans back into the tank. We also used those same containers to buy more fuel from a nearby Pemex station and ferry it to the boat. Right now we have about 80 gallons of fuel aboard, enough to last us a few months. Being able to refuel the boat in this way gives us greater flexibiltiy and we can take our time and filter the fuel without feeling rushed at the fuel dock.

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This is our Baja Filter. The tall cylinder holds the three filters you see on the left. The filters provide progressively greater filtration in the order shown. In practice, that green filter on the far left gets almost all of the abuse and Melissa had to clean it with soapy water and a brush more than once.

Along with our fuel polishing project, I changed the Racor primary fuel filters, and engine’s secondary filter. At this point I think we are protecting our precious Beta Marine engine better than most boats. We have never had the engine shut down because of a clogged filter and, Lord willing, we never will.

14 thoughts on “Dirty Diesel Done Cheap

  1. Nice writeup. You’ve inspired me to do the same thing. I’ve worked over every system in my boat but have never inspected my tanks, though it’s been on “The List” since I got her. Fortunately, I’ve got two equal-sized tanks and one is empty at the moment so I plan to clean out the empty tank and then refill it from the full tank (through the filters) before cleaning the second tank. Don’t be jealous, I’d gladly trade my twin tank setup for your wonderful bulkhead-mounted filter and strainer setup!

    • Having two tanks will be very helpful. Hopefully both have good access. Our tank actually has two plates but one would require a major disassembly of the interior, including removing our steep companion way steps.

      The duel filter setup has been very nice. When I installed it I really wanted to buy the racor drop in filters (500 series?) but could not justify buying those when I had three of these older style units. I have been told and read that a vacuum gauge would be a valuable addition to this setup.

      • I’ve got the dual-Racor setup and a vacuum gauge is very helpful. Unfortunately, mine has an older style gauge that doesn’t have a peak-hold indicator so I have to open up my floorboards (where the engine lives) to see the gauge while the engine is running at high RPM under load. If you add one, make sure to get the peak-hold needle so you can check it on a mooring with a beer in your hand. It’s never bugged me enough to change it but if I were goin’-a-cruisin’ I would.

    • Glad you can relive the good times all over again with us Steve. I have a post about water heaters in the works that should make you glad you didn’t have one.

      • Ooooh, I can’t wait! My water heater is a ticking time bomb that hasn’t gone off yet but I’m hoping I don’t have to change it until next winter. In the meantime, it likes to pee itself just a bit and doesn’t get along with those newfangled shore power pedestals with GLCI breakers. Eh, what’s the worst that could happen?

        “Ummm, Honey? When you turn on the faucet just give it a quick tap and quickly pull your hand away…”

        • That certainly puts some excitement into your dull dishwashing routine.

          Well depending on your tolerance for pain. The repair of a water heater like ours (isotemp spa15) can be done pretty cheaply. If you don’t count first aid supplies.

  2. Michael, just to let you, and Melissa know who I am.

    I am Keith, the husband of Paméla, which was one of your fellow Sound Transit commuters, southbound to Tacoma.

    Paméla introduced us to each other one day/evening, a week or two before you retired from work.

    Again, this is just so you have a reference to who I am.

  3. Great write-up Mike. glad you both kept your senses of humor…

    Good thinking and problem resolution.

    We were lucky in that the previous owners did all that and we are still squeaky clean in both fuel tanks.

    I agree with the comment about having a vacuum gauge with the telltale indicator. Very useful to be able to see max readings anytime.

    Another thought, and perhaps your fuel system is already set up this way… [I’ve done this on all 5 of my boats and it has saved me several times…]

    Since you have a 12V DC fuel pump in the circuit [ostensibly to prime fuel to the engine, as as a back-up to the (low pressure) fuel pump on the engine]: there is likely a strategic location in the fuel lines where you can add a multi-way valve [e.g., 3-way] to recirculate fuel from the tank, through your Racors, and back to the tank— thus being able to polish fuel anytime. [We also use this set-up to transfer fuel between our two fuel tanks…]

    True there are fuel polishing system on steriods, but with your Baja filter [I still have mine from the 80s…] and occasional recycling theourh the Racors, you will be in good shape.

    In case this is something of interest…

    Cheers! Bill

      • that could be an advantage. The downside is that the engine would run for a few minutes before dying, creating a potential for damage due to loss of control. I think I’ll stick with my start battery switch. We have had reports recently of boats being stolen here only to find out later that there were conflicts between multiple owners. In most anchorages, we leave the key in the ignition and the boat is fully ready to go if we are away for less than a day. Our thinking is that if we are away and an emergency arises, we want whoever boards her to be able to get underway as easily as possible. Think dragging anchor, or having a boat drag down on you.

    • That is a great idea Bill and in fact I already have a two way valve setup on the return line that I thought would be handy for priming or sampling the fuel. With a little rerouting, I could plumb the outlet from the filters to a valve that could then switch to the engine or the return line. The volume would not be too great but we are not used to doing anything very fast aboard a boat named after a tortoise.

      I also have a higher volume transfer pump that I can use to send fuel to the heater’s day tank and a second fuel tank. We actually have a 72 gallon tank that I have never used and am not even sure if it contains fuel. If we were to travel to very remote locations or very high latitudes where we would need to heat the boat, I would probably care more about using that tank. As it is, we have enough fuel for most of a year’s travel.

      I would be interested in your recommendation for the vacuum gage for fuel. It is something that would be easy to install and I could pick one up when we head north later this year.

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