Updated: May 19, 2021
As noted, this has nothing to do with CW. But this came up in discussion twice the past few days in conversations with other boaters when things turned ultimately to protecting the motors on our tenders, which turned into how I protect much of my machinery. I thought I'd put this here as I've seen a lot of boaters worry about this more than the average "civilian" and not just with their outboards but everything. This went out as an email to a small number of primarily mechanical friends several years ago. Pasting......
Literally all I do is fix and make things and solve mundane problems (and not the fun/interesting kind) that never should have come into existence in the first place but I have pretty much stopped posting project reports (couple per week) for time reasons. Since I'm the guy who takes care of all of my motorcycles (15 carbs on 6 bikes), both tractors and various lawn equipment, 3 generators, two chain saws, the cars, and at least for several years, my dinghy's outboard, methanol-driven internal fuel system harm is something I've dealt with dozens of times. Not just like some who watch one or two YT vids and poof...instant expert problem solvers pretending to have figured something out. I actually have been fixing it for over 25+ years (thank you corn lobby and eco-utopian fan boys).... know what it looks like... where it happens in the fuel path, and where it doesn't happen. In fact, YT and online forums/tribes have become so choked with enthusiastic know-nothing never-done-squat types that they are simply 100% useless in most cases. They film the first time they stumble through something and narrate in a tone like they're teaching, and everyone with significant actual saddle time owe them some measure of fealty to treat them as equals.
Using my primary generator to demonstrate this "modular system"... but this works on all my engines, 2 or 4 stroke. For now, I only do it for my 4 strokes for no reason other than they have larger fuel tanks which makes the cost savings worth it.
I could run my 4 strokes exclusively on engineered (corn-free) fuel but I don't, though I'd like to to stick it to those pirate corn farmers remorselessly screwing up the country's machines so they can sell their commodity at commodity-plus prices. POE OPE, as they say.
I never once found evidence of corn pollution in my fuel tanks.. only in the small volumes and passages of the carbs. Some carbs. Those that sit for periods. What I do facilitates rinse-displacing the corn crap from the carbs of my 4-stroke machines... let's me leave the stabilized corn crap in the big multi-gallon tanks where it it doesn't hurt anything or degrade very fast. It lets me leave real fuel (methanol-free) in the carbs greatly reducing the odds of getting corn cancer in all my machines. Further, with the way I do it, I only use a small fraction of the expensive real fuel and save work to boot by not swapping fuels in the tank when done.
Note... despite claiming to be stabilized, I don't believe them and add my own to the real fuel. Almost no downside. Second, I run all my 2 strokes using 2-stroke premix which I also properly stabilize at the end of the season and run thru the carb before putting it away. If I have a big project for the chainsaw, I mix up some castor oil and corn crap and use that for most of the project, and then use the premix with added stabilizer before putting it away. All engines are exercised monthly using real fuel... corn crap is only used for bulk work and is otherwise banished from all of my machines.
I distribute real fuel using an add-on fuel tank that I can hang off my motorcycle lift or directly on the heavier machines... it doesn't show but the mast is rebar with a hook bent into the top and cut to a length that let's the fuel not end up dramatically higher than the built in tank to avoid pushing past the float needle. Note it has a petcock at the bottom.
Inlet port for real fuel
The machines are fitted with quick disconnects (the white thing on the left) so I can add/remove the aux tank without burning a lot of heartbeats screwing with dragging rubber fuel lines on/off barb fittings.
A second advantage is that I can quickly attach a drain hose at this port to, for instance, pull a little gas off the bottom of the tank where water is likely to live because some collection of AH's brilliantly made us all put a hygroscopic fluid into all of our fuel tanks. At least we don't have that mandatory air-bubble-into-artery-injection law to deal with yet to save the syringe industry.
Besides just draining some off, if the drain line has a filter in it, you can use the machine itelf as a pumpless fuel polisher.. just run it into a clean tank... shut off the corn-crap-metastisis control (petcock) and pour it back into the tank.
The added path for real fuel
This mod is nothing more than adding an extra path to the delivery choices for the carb, with appropriate shut-offs. The machine's built in petcock stops the corn crap from metastasizing into the carb when it's not "needed" (not to imply that anyone other than a corn farmer needs that stuff to be in your tank in the first place). The shut off from the aux tank path prevents the corn crap from flowing directly on to ground... where honestly, it actually belongs.
Just a slightly different angle. The loop looks bush league but I did it for two reasons... to prevent any off-angle load from bearing on the machine's petcock which is only a press-fit into a grommet, and to prevent having to disassemble all the way back to the carb to add a new just-long-enough length of fuel line should I need to remove (with a knife) the filter or tee from the carb line.
Some bullets on the thinking driving this... (this may be redundant given the nature the original material was disseminated).
Fuel with methanol, particularly when left to sit.. particularly when left unstabilized with a methanol-informed stabilizer, corrodes and otherwise clogs fuel systems.
These effects, in my experience, take place primarily in the small passages and volumes inside of carbs first.. and then after a huge amount of time, in the large ones like the bowl. Other than rust in a partially filled metal tank or hygroscopicaly attracted water pooling at the bottom of one, I have not seen any significant issues in a tank. I can't comment on the physics that drives this "smaller first" behavior but.. as with Ignatz Semmelweis and hospital fever, I lack an explanatory theory of it and will be derided by Google-smart "experts", but I do have a death grip on the relevant phenomenology (sorry... I used to be useful and don't get to pull out the good vocab anymore here in the Land of Yuppies).
I keep significant, aggressively-stabilized fuel reserves that are cycled out every 18-24 months. Not once did I ever find water in a sealed storage tank and I use my Plus-One rule every time, so if it's there I'll see it. Further, I've rebuilt way way way too many carbs over the years (says the guy with two cop bikes with 4 carbs each. And the CV type to boot). It's not in my best interest to just phone this in.
For a long time, my only "system" was to just start the engines maybe monthly. I have not seen a discernible improvement which I attribute to 1. I wasn't being plagued by problems to begin with and 2. I am aggresive with stabilization, and also, I use one formulated for fuel with methanol. Sometimes I did find a carb that needed to be cleaned but it was rare. The initial mitigation handled a lot of the problem.
I eventually moved to race gas and/or Trufuel/equivalents with added (by me) stabilizers to evict the corn harm from my carbs before storing a machine. I'm cheap as hell.. and lazy to boot so I don't waste heartbeats pulling the ethanol-tainted fuel out of the tank when I'm done with a machine for a season and then pouring in race gas, running it in, and using that for the first tankful next time. WAY too much work. Way too spendy. And way too much to store. Race gas is about $28/gal at the low end and up to $60 and more if you simply must have your special brand like Stihl or Husky or VP or whatever. Of course, each boutique brand obviously has their own refineries and just use the same containers because it's good for the environment. For me... I stabilize with my preferred chemical and then only use as much race gas as necessary to solve the actual problem.
For a long time, I would pinch off the tank with the ethanol it it... pull the fuel lines apart... and run some stabilized race gas in using a soup can with a petcock mounted in the bottom. Run it in and then shut it down. Still a PITA.
Recently, I started adding a permanent extra fuel inlet path to my 4 stroke machines to which I can attach a movable/removable auxiliary tank I can mount near/on each that connects to the patient/machine with a quick-disconnect fitting. This QD allows other "modular" accessories to be used like drains and gravity polishers. Flushing the distributed corn crap out couldn't be faster or easier or lower cost.
The pix show what I came up with, which in the end is a pretty simple setup. This hardware is being run out to my 4-stroke machines...
the "big gen" (shown in the pix)
the "medium gen"
the "big leaf blower"
the "little tractor"
and if I can find it, the trash pump (did I loan this to anyone?)
I'm not adding it to the bikes because I don't want some AH opening up the valve on the AUX IN leg and draining my entire tank. Not sure what I'll do on this. Ideas welcome.