Bad Gas info

[Vince_o]

Well with the info that Ive been taught from the good folks at Kohler, Kawasaki, and Briggs, I thought I'd pass some along. I'm not saying this is 100% right, but it is some facts that I have to go by doing warranty work.
Our shop is classified as a Expert dealer through Kohler and a Diamond Dealer with Briggs. That all has to do with training with the employees that work there, and the level that they have achieved. So far Ive passed just 3 of the 5 Master tech courses for Briggs, the electoral one is KILLING me and Id like to do the one for Kohler, but they only offer it in WI, so that aint going to happen any time soon. I study as much as I can while we are slow this time of the year in he shop with online courses. This post is generated from the 682 post with a carb rebuild and few weeks later it doesn't run.

The ethanol as much as we hate it, is here to stay. For me and my customers, its about 80% of our complaints on a non running or rough running engines. I see more Briggs than any other. This may be just the fact that they are more prevalent on the $799 to $1400 dollar mowers. Very rarely do I see it in the commercial guys stuff, reason, they don't stop running it. If I do see it, its in a 2 stroke or a 4 stroke hand held. You take your pick, Stihl, Shindawia, Kawasaki, Ecco, Huskvarna, to the big box store stuff, if you don't use it, it will have problems.

Some folks swear by Stabil. In the past Ive used it for years. Ever notice when you drag that old garden tractor out of the barn that hasn't ran in 10 years, you clean the carb, use the old gaskets, and next you know its belching black smoke and mice out of the muffler when you bring it back to life. The reason is that it had pure gas in it 10 yrs ago.

The way it was explained to me at the Kawasaki school a few weeks back is in the molecular structure of the atoms in the formula of ethanol. (That was a series of 10 dollar words for me) Meaning the molecules of the ethanol attract the water ones and they, for a lack of a better term or to keep up with the kids today, HOOK UP! Then in turn react to each other and start the process of ruining the rubber in the fuel lines and in the plastic of the carbs.

Now a lot of the bigger engines, like in the Kohler 22 and up, there's more metal and brass, remind you of the old Carters and Walbros we have, so there less rubber to destroy. With the onset of fuel injection to the industry this will take care of a lot of this. The fuel injection Ive seen on the Kawasaki, isn't like what would be in a car or a diesel semi, more of just a pump of pressure. This will allow more of the now larger molecules of water and ethanol to pass and burn. Please bear with me cause I cant type everything I learned in 4 hrs of fuel systems in one post, its just a basic idea, the way I interpreted it and under stood it.

I know Matt has a write up on building carbs, and don't know if he went into what the circuits do, or how they blend the air fuel mix. Basically carbs are vented, internal and external. Our old Cubs, and others, with the older Kohlers, have external. That's why you'll see fuel leaking out of the carbs, and into the air cleaner. The vent lets the barometric pressure push the fuel. Fuel pumps aid in this too, but for our K series we use gravity feed mostly.

You have a low idle circuit and High speed circuit with a transition in between. There's a Welch plug on the side, if you've NEVER removed one, BE CAREFUL, if you take a chisel and go too deep, your ruin the carb. Behind the Welch plug is very small holes that if get clogged, will not allow the air and fuel to mix. When the water and ethonal mix, youll get a jelly looking or a whit crusty looking bowl. If you cant get these out of there, your carb will never run right. You can soak it till your blue in the face, it wont work. Many times we here people say I rebuilt the carb, but they couldn't get that little jet out at the bottom of the emulsion tube. That really needs to come out and cleaned along with the Welch plug.

So that said I'm going to post a few picks of bad gas we've seen at the shop. Remember if you buy something to STABLZE your fuel, it has to treat the ETHANOL. Regular Stabill won't work anymore as it makes a wax like coating on the carb. In today's carbs, the needle is usually made of some type of rubber, there for a leak will occur when the white build up comes between the rubber needle and the brass seat.

These are from a Tecumseh engine on a Toro push mower. It was so thick with gum it stuck the intake valve.

[Vince_o]

Here's some from a 4 stroke TSC go cart thingy. Sat all winter and this is what it looked like 4 months later. We see lots of green gas at the shop.

[Vince_o]

This is the white stuff I was talking about. I took this out of a cyclops Cub when I first went to work at the shop. If this gets into the Welch plug area you'll never get it out just soaking the carb.

[Vince_o]

A few weeks back I worked on a crapsman with a burnt exhaust valve. It needed carb work too, & just a good cleaning. It was on a leaf vac, so there was dirt in the bowl. I cleaned it and rebuilt it. Frank did a valve guide and valve job on it and I finished it early the next morning. Later that same afternoon his son came up the the show room and told me my carb had leaked all over the floor, I was pissed. rebuilt it again, and next day the same thing!

This time Frank was with me, as soon as I pulled the new fuel line it stretched like a rubber band. We looked at each other and looked at our fuel can. Here's what we found in our fuel can that Frank's son had filled up the day before.

Looks like corn oil to me, trashed all the rubber parts in just a few hrs!

[EricR]

Great write up Vince.
Later this week (when it warms up a little) I'm going to pull the carb and fuel system apart on my 102#2 as it has the same problems as your pics.

[ACecil]

Thanks for the info and pics, Vince! The pics say it all.

[green 4 acres]

Yea and its debateable if it even saves a noticeable amount of energy as it takes a lot to produce . E 85 is dead here in my part of MO
I do not want to use 10% in my exper. plane and may get non ethanol in Garder ks. It is about .65 more a gal but it needs premium and hard to tell if it is old some of the pics seem more of old fuel problems sticking valves also dont forget about mge additive

[TSWolf]

There is an ethanol treatment/stabilizer out now called Startron, it works great.

[72-149]

i for get the name of the stuff but i buy it at the harley dealer to get rid of the ETHANOL its like $8.00 a bottle .it is BS that we have to deal with this as americans ,pay to have them reck are stuff & its ok with the gov. to do this to us & dont care

[72-149]

Originally Posted by Vince_o

This is the white stuff I was talking about. I took this out of a cyclops Cub when I first went to work at the shop. If this gets into the Welch plug area you'll never get it out just soaking the carb.

my buddys rototiller was acting up so he had me look at it and low & behold it was running like crap so i took the carb off & that same stuff was in it cleaned it blew it out new gaskets & put it back on 10 min. later it was leeking all over the place