Unusual fuel deposits in carb

[Streblerm]

Not exactly chainsaw related, but it could be. The carb in question is off a 16hp Kohler that was running erratically. I pulled the carb off and there was some water in the fuel bowl, but also little balls of gel. when rubbed between the fingers the gel balls would break down easily, dry out, and feel a bit gritty.



The body of the carb had a yellow powder that instantly washed away with a bit of solvent. I am thinking it is the gel balls dried out. It isn't corrosion.


Anyway, a little cleaning and a new fuel filter and she is running like a top again. Has anyone ever seen anything like this before?

I am concerned that it could be a lined fuel tank breaking down. The tank was lined with KBS tank sealer a couple years ago. That was the last time the carb was cleaned. It is in a small bobcat that sees infrequent use.

 

[HarleyT]

A probable combo of water, dirt, fuel additives, alcohol/aluminum corrosion, etc...
If the engine sits a long time, best to drain the system, as well as the carb. {Loosen the bowl nut}.

 

[pioneerguy600]

I see that any time water gets inside an aluminum carb, around the saltwater here I see it more times than I want to.

 

[Smokepole]

Typical "white rust". If you need it to run in an emergency, better put 100% gas in it.

 

[sunfish]

Ethanol in the gas.

 

[GPX433Todd]

The gel balls are from ethanol in the fuel.

 

[Bilge Rat LT 20]

Ethanol will dissolve/solubilize all sorts of stuff, tank linings, rubber, plastics, even fiberglass resin from glass gas tanks.

The crud is in solution so filters don't catch it.
Now you run the motor getting it hot then shut it down. The fuel in the carb/injectors/ fuel system soaks up this heat then cools off sitting there.
This heat/cool cycle is the start of bad things, upon cooling the crud drops out of solution reforming into the sand, brown crud.
The ethanol continues to attack metal, plastic,rubber, and attract water that corrodes/rusts stuff too.
The globs are ethanol/water crud balls.

It doesn't happen in the main fuel tank but near the motor heat it shows its ugly self.

We see it in boats, outboards, 2 and 4 strokes.

Ethanol resistant fuel lines are not ethanol proof, they dies in 2 to 3 years with the use of the corn juice.

In rarely used equipment use 100% gas and just a little marvel mystery oil, 2 stroke oil etc, for a little lube to protect the fuel parts. Ethanol Kills!!!

 

[drf255]

Ethanol has ruined many of my low use engines.

Same deal, dry yellow resiny deposits in the carb that Gumout and boiling will not resolve.

 

[Streblerm]

Well, I'm glad others have seen this. I have run into white rust before but never this yellow crap and little gel balls. I guess I use all my other stuff frequently enough to avoid this. The interesting thing is that lacquer thinner which is mostly acetone and methanol instantly dissolved both the powder and gel. No scrubbing required.

My biggest concern was that it was the tank liner letting go. Tank removal means engine removal. Last I checked the tank was $800 from bobcat. When I heard the price I didn't even bother to check if it was even available.

This is my first ethanol related problem. At least it is on a carb that can be removed, rebuilt, and installed with little more than a screwdriver. I did find a station near work that offers ethanol free gasoline. Looks like it is time to start going there.

 

[HarleyT]

A lot of what you are seeing is the result of water and ethanol, the ethanol mixes with the water to help burn it through the engine. Without the ethanol, water will still condense and sit at the bottom of the carb and do damage, so draining the system on your engine is still a good idea.

 

[sunfish]

Besides running E-Free, store equipment inside, or at least under a roof of some kind and keep the fuel tank Full.

 

[Streblerm]

A lot of what you are seeing is the result of water and ethanol, the ethanol mixes with the water to help burn it through the engine. Without the ethanol, water will still condense and sit at the bottom of the carb and do damage, so draining the system on your engine is still a good idea.

View attachment 443037

That's funny. That picture looks exactly like what happened to this carb a couple years ago. I had left it outside for a couple months and when I needed it, no start. The fuel bowl was totally full. Floatsicle anyone? The throttle shaft sticks out the top and it has a bit of slop. Not enough to make it run bad but enough to let melting snow in.

Besides running E-Free, store equipment inside, or at least under a roof of some kind and keep the fuel tank Full.

It does sit inside. Either in my insulated garage or at least under a lean-to with three sides enclosed. The last time it was stored outside was last summer when it was on loan to my FIL. It ran flawlessly all winter after that. I've probably run 10 gallons through it since then, all with Marine stabil.