Fuel Stabilizer for Marine Gasoline Engines (And Ethanol Too)
IntroDuction
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As a full-time liveaboard, I have absolutely had more than my fair share of issues with small engines, usually in the worst possible conditions on the worst possible day.
On land, when your weedwacker or lawnmower won’t start you’re in for a frustrating experience. Even worse, and possibly dangerous, is when your generator won’t start during an emergency. As a liveaboard, you rely on your small engines, every day, like land lubbers rely on their emergency back-up generators. When your small engine, like your outboard motor, doesn’t work, it can ruin your plans for the day, or possibly strand you in a dangerous situation.
Last year, when it came time on a cold, rainy, windy April day to move my sailboat home from my winter liveaboard slip to my summer mooring, I ended up stranded in the middle of the river; getting pushed out by the fast outgoing tide. Due to water-contaminated fuel that I had “stored” through the winter, my outboard went kaput in just the right amount of time for me to get as far away from land as one can on the Piscataqua. It was zero fun. Luckily, my friends were a phone call away for a quick rescue.
Sea stories aside, my point is that boaters rely on their small engines and need them to work. Since we starting blending ethanol into gasoline in the US in the mid 2000’s, keeping small engines running reliably has become a challenge. After stubbornly fighting the facts for a long time, I’ve struggled with enough small engine carburetor issues to come to the conclusion that, if you’re using gasoline that contains ethanol, you absolutely need to treat it as soon as it comes out of the pump.
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Resources
Project Farm Fuel Stabilizer Test: https://www.youtube.com/watch?v=UvS_D4_lF5U&t=5s
This is an awesome, quick test by Project Farm (simply the best) of the effect of ethanol-containing gasoline on small engine carburetors. The amount of corrosion and “gunking” that forms in ethanol fuel, when it sits, is shocking. If you’re impatient, zoom to 5:40 in the video.
Pay special attention to the gunk that builds up on aluminum when it’s exposed to ethanol/water.
PF tests Lucas Oil Safeguard Ethanol Fuel Conditioner. Based on the results of his testing, I would not recommend this product.
Taryl Fixes All 19-month Ethanol Fuel Stabilizer Test: https://www.youtube.com/watch?v=iWL7p0Pnb8Y&list=PL-xkNBjnenDA3DyuEhAL10PgZ19A72rz5&index=19]
An awesome, scientifically-inspired fuel stabilizer test on separate, brand-new mower engines. It’s a lengthy watch, but it’s worth it if you’re interested in seeing what products really work to stabilize ethanol fuel.
The product I am recommending (and use myself) performs very well in the test.
University of Nebraska study Ethanol and Water Contamination: Results and Observations: https://cropwatch.unl.edu/documents/Ethanol%20and%20Water%20Contamination%2009052014.pdf
Project Farm Can K100 Make Water Burn?: https://www.youtube.com/watch?v=MbPPjTsvPyo&t=198s
This test shows that once the ethanol in the fuel absorbs enough water to phase-separate, it’s very difficult to make recombine with gasoline and/or make it burn again.
Database for non-ethanol gas: https://www.pure-gas.org/
Why Does Ethanol Cause Problems for Small Engines?
The main issue at work is that ethanol (an alcohol) is hygroscopic (it absorbs moisture in the air) and gasoline is hydrophobic (it resists absorption of moisture). When ethanol is mixed with gasoline, the ethanol can only absorb a small amount of moisture before the ethanol/water blend falls out of suspension with the gasoline and settles at the bottom of your fuel tank or carburetor. Your engine can’t burn this water/ethanol mixture, and you end up with an engine that won’t start, or won’t stay running. Check out some of the links to the Project Farm videos posted above. The phase separation between gasoline and water-contaminated ethanol is very obvious.
If the water/ethanol mixture isn’t cleaned out, it can cause corrosion issues inside the fuel system (carburetor). When this happens (it generally happens fast in the marine environment - I’ve dealt with it a lot), just changing the fuel out usually won’t fix the issue. The engine will still run poorly, or not at all, due to fuel delivery issues. Generally, the corrosion isn’t so severe that a quick carburetor cleaning won’t fix it, but that’s still a pain when you’re trying to be somewhere!
Why Sta-BIL Marine 360 is Essential
Sta-Bil Marine 360 helps water/ethanol fuel issues tremendously when you add it directly to your fuel can at the pump. It buys you time, resisting water contamination and preventing corrosion in the carburetor. I resisted the added (small) expense and extra effort of adding Marine 360 to my small engine gasoline, but I always seem to to end up getting bit by an engine that won’t run after time (a month or two), then needing to go through the time and effort of disposing water-contaminated gas, and needing to clean out a carburetor when I have something important to do.
After too much frustration, I became a big believer Marine 360. For small engines, I recommend buying the 8oz or 32oz sized container because they feature a handy dosing tool right on the bottle and clear instructions on the back. 1 oz treats 10 gallons of fuel, so an 8 oz container (at $10) will treat 80 gallons of fuel; a decent value proposition.
My Take on Other Sta-Bil Additives
In my experience, Sta-Bil Marine Tune-Up and Sta-Bil Fast Fix can be somewhat helpful to clear up light-duty carb issues causes by ethanol/water contamination after all of the contaminated fuel is replaced in the fuel tank and the carburetor is drained of contaminated fuel. In my experience, it has only bought me time until I needed to clean the carb. It can be helpful when you’re in a rush, I’m not knocking it, but nothing replaces cracking the carburetor and cleaning all of the little orifices with spray carb cleaner. Any kind works great. Carb cleaner is nasty stuff and tends to go everywhere when spraying it. Be sure to wear eye protection and gloves! Follow all safety protocols recommended by the manufacturer.
If you’re not going to be using your small engine for an extended period of time, I recommend draining the carburetor bowl or running it dry as a good safety measure against corrosion issues. Marine 360 helps prevent corrosion in the carburetor, as well. I believe that stopping corrosion in the carburetor is the primary reason for why it is so effective.
Fuel/Water Separators for Dinghies and Small Boats
Racor S3240 - Essentially ends small marine engine water/fuel issues
I’m convinced that one of the best, if not the best, investment you can make for your dinghy is a small, Racor Fuel/Water Separator. This will largely put water/ethanol fuel issues in the past. These can be a little intimidating to mount for some people, as they require either thru-bolting through the rear bulkead, screwing into the fiberglass core, or gluing a backing plate that you can screw into. Still, this is the most fool-proof way to prevent water issues. The bulk of the parts you will need are listed below, but with any plumbing project, I prefer to shop for fittings locally so that I can return or exchange things easily.
Port Size: (SAE J476) ¼”-18 NPTF
Sea Choice Straight 1/4” Thread x Barbed (3/8” or 5/16” barb): https://amzn.to/3tsZT83
Sea Choice 90 Degree Elbow 1/4” Thread x 3/8” Hose Barbs: https://amzn.to/41BNn2u (due to space constraints, this 90 degree barbs may fit better)
Sea Choice Fuel Line: https://amzn.to/47dgZV6 (or use your existing fuel line if it’s in good shape. Note the size of your existing fuel line to make sure the Racor’s hose barbs match.
Aviation Form-A-Gasket: https://amzn.to/4atNu4t (for fuel-line fittings, I don’t recommend using teflon tape/plumbers tape as it can break off and get stuck in fuel orifices)
304 or 316 stainless steel mounting hardware
Stainless steel hose clamps
Sika 295 UV for Sealing Mounting Hardware: https://amzn.to/3GTeuNb
