Run Carb Dry or Not.-

[Sea Rider]

It all depends on your boating location, boating the whole year round or juts in summer, spring in colder climates. The worst you can do to a 2 stroke Tohatsu motor is leave the entire fuel system full of fuel specially if running E blended fuels for long time periods. To avoid screwing all the internal carb's metal parts, the fuel pump's diaphragms and the entire fuel hose, keep pressed the tanks connector with something pointy till the motor drops dead, take advantage to flush the motor much longer while doing so. Pics speaks for themselves

Happy Boating​

 

[MattFL]

It's the ethanol that is the major problem, it absorbs moisture from the air and creates a corrosive goo that just corrodes everything, as your pictures show. It's a major problem in humid places like S. FL where I live. If you have the option, use ethanol free gas, it really does make a difference, especially on a carbureted motor. Running it until it stops is good, but that still leaves a little bit in the bowl. Opening the bowl drain is the best if you can do it, then spin the motor over to suck any remnants out of the jets. Every motor is different, but a couple of motors I have here will give another teaspoon or so of gas from the drain after it appears to run out of gas. To go a step further, I've had the best luck by soaking the carb with fogging oil after draining it. If the motor gives you access, remove the slow speed jet and shoot some into the carburetor that way to really get it in there. The oil will help protect the metal from corrosion.

 

[Sea Rider]

Don't have non E fuels any more due to being a lucrative business growing sugar cane, installing E plants and selling the by product to gasoline distributing Companies.

A faster way to burn all the fuel leftovers if any inside the carb when the motor is about to die of fuel starvation is to pull choke out, in several times in a row while throttling. Don't have such issues as seen on both pics as usually boat all year round and run bowl dry each time returning to terra firme taking the advantage to flush the motor with fresh water for as long as 5 minutes.

The first pic it's from a Tohatsu 5 HP motor, the second one from a Tohatsu 9.8, both motors were found dead and readily available to be used as anchors. Both carbs were brought back to 100% operational life without changing any internal component. Long hand cleaning, bishop's patience and many cold ones did the trick. Nope, we don't have a Tohatsu dealer around the corner to buy a carb kit...

Happy Boating​

 

[MattFL]

We still have non-E gas here, for now, but they get an extra $1 or $1.50/gal for it.

 

[dingbat]

Have not drained a carb in a single piece of equipment I own in over 20 years.

Add stabiler to the fuel prior to last use of the year and put it away.

 

[MattFL]

Have not drained a carb in a single piece of equipment I own in over 20 years.

Add stabiler to the fuel prior to last use of the year and put it away.

Where are you located? Stabilizer is not good enough in Florida. Even stabilized gas starts turning yellow after a couple of weeks and turns to goo if you leave it long enough.

 

[ahicks]

You know what doesn't turn (for a couple of years)? Good synthetic 2 stroke oil mixed in a 50:1 ratio and run in your last tank of fuel for the season. Just something to consider....

I use it in 4 stoke motors that aren't going to be used for a while, pretty much everything I work on, plus my lawn care stuff. Coats everything it comes into contact with a thin layer of synthetic oil (cylinders, rings, valves etc). And there will be NO noticeable smoke created while running it! The built in fuel stabilizer won't allow the pilot jets to gum up.

That said, the Honda carbs and injected motor vapor separators are so easy to drain, there's just no excuse not to if it's going to be sitting around unused for more than a month or so.

I would NOT try this 50:1 trick in an injected motor using an oxygen sensor!

Not a new trick, nor one I dreamed up. It was shared by a long time Florida marine mechanic that I trust..... Use it if you like, or write it off as crazy. I don't care.... -Al

 

[dingbat]

Where are you located? Stabilizer is not good enough in Florida. Even stabilized gas starts turning yellow after a couple of weeks and turns to goo if you leave it long enough.

Mid-Atlantic coast

Keep 150 gallons of both diesel and E10 on property (275 gallon tanks) year round for use around the farm.

Both tanks get treated when filled. Roughly once every 10 months. No problems with either in the 20+ years with the exception of the time I forgot to add Cetane to the diesel.
It rarely get cold enough to need it but this was one of those times..Slurpees in the fuel filter while

The boat has a150 gallon capacity. Use the boat until Striper season closes December 31 or water temps drop below 45 degrees, whichever comes first.

Like I said, I run stabilizer the last few outings then park it until March. Top off the tanks and go boating.

I’m interested in this phenomenon that stabler doesn't work in Florida. Any technical data you can share or strictly antidotal evidence?

 

[MattFL]

It's the humidity. The ethanol in the fuel absorbs the water right out of the air and creates a mess. This is the closest to a scientific study that I have, but his results match my results perfectly. FF to about 12:38 for his summary:

The small carbureted 4-strokes suffer the worst. I've had several, several small dirt bikes (4), 6HP Tohatsu outboard, etc.. Like clock work, if you leave ethanol gas in them (with stabilizer) the pilot jets clog up after just a couple of weeks and they have to be cleaned to run right. If you leave them long enough the main jets will clog up too. The gas you drain out of them is always yellow and it leaves a yellow film around the carburetor bell. Even my 50HP Honda will get clogged up if I leave it with ethanol gas for more than a few weeks. The bigger fuel injected engines don't seem to be as sensitive, probably because the fuel system is sealed and the gas in the injector isn't going to absorb moisture.

Edit--> If you're running mostly big farm equipment, that might also explain why you're not having problems. For one it's running all the time, not sitting. And for two the jets in the carburetors are enormous as compared to small 4 strokes.

 

[pvanv]

Of course everyone prefers E0 fuel. But one marina here in Buffalo has E10 with ValveTect additive. Have had no issues topping off in the fall and restarting in the spring on 115 hp EFI motors. But on a sailboat, where the fuel sat for 2 years, the fuel in the tank was so bad that it had to be dumped and the tank scrubbed with acetone. Seems the second winter is what gets em.

 

[Sea Rider]

Anyone is doubting that E8-E10 will not screw all the internal metal parts a carb works with along rubber parts such as fuel pump's diaphragms if fuel sits for too long time on them. Not to mention the carb's outside color discoloration and fuel filters as well that will experiment with E fuels. If using 3-6 gal portable plastic tanks better burn all the fuel from tank to carb on last boating day when going out of season.

Happy Boating​

 

[dingbat]

The small carbureted 4-strokes suffer the worst. I've had several, several small dirt bikes (4), 6HP Tohatsu outboard, etc.. Like clock work, if you leave ethanol gas in them (with stabilizer) the pilot jets clog up after just a couple of weeks and they have to be cleaned to run right. If you leave them long enough the main jets will clog up too. The gas you drain out of them is always yellow and it leaves a yellow film around the carburetor bell. Even my 50HP Honda will get clogged up if I leave it with ethanol gas for more than a few weeks.

All the "big equipment (tractors) are diesel.

The rest of the equipment are small to medium sized 2 and 4 strokes (golf cart, 4 wheeler, big and small carburated outboards, generators, chain saws, garden tractor, trimmer, etc.)

Some of the equipment, i.e. garden tractor and generator, sit months between uses. Others, like the blower and trimmer, sit 3-4 months during the off season. Have not had any issues since getting serious about treating the fuels upon delivery.

The white material in the aluminum carbs is the result of alcoholate corrosion, although other forms of corrosion also exist when aluminum is placed in a aqueous solution.

The interesting part of the phenomenon is that the corrosion is in fact from a lack of water in the fuel.

Ethanol can carry up 0.05% (temperature dependent) water before separating. Without oxygen (H2O), aluminum's protective layer (aluminum oxide) can't replenish itself, leaving it vulnerable to attack. Studies have shown that water levels of 0.1% can be sufficient to enable the passive surface oxide to remain intact.