carbureator icing

[ac45]

I had a funny thing happen to me it was about 15 degrees out, and I had been cutting. I had ran the saw out of gas, and quit and was loading my would trailer, about half an hour latter I gassed the saw up, and it would not start for anything. I fiddled with the carb, and still nothing. I took it back to the house, tore it down and everything seemed alright. carb had been rebuilt about 3 weeks earlier, from a similiar incidence, the next day it was above freezing, took saw out and it performed fine,Just what are the smptoms of a carb icing? I usually dont cut much, when it is below freezing, or at least much below 25 I think that condensation had been forming in the carb, and when the saw cooled back down it froze in some of the passages in the carb. Is this possible?

 

[geofore]

ran out of gas?

Doesn't that saw run at high speed just before it runs out of gas to warn you it is about to run out of gas, filter sucking air and gas just before it runs out? Ice crystals could be clogging filters. Mine did that at -10F, it was the filter, got a little snow in it filling it with gas. agravating

 

[sedanman]

The only carb I ever had freeze on me was on a Honda Civic. The car steadily lost power and was running VERY rough (RICH) before it cut out. I let the car sit a few minutes and then it re started but not easily as now there was quite a bit of water in the intake manifold. It took another occurrance of this for me to figure out the problem. The ice forms in the venturi effectvly choking the engine to point it becomes too rich to run.

 

[Jumper]

I experienced this on a really cold day last year-saw including the climbers would not run worth a hoot, so we called it a day; the temp being -20F . Dunno if a little gas line anti freeze would hurt saw gas or not, and also make sure you are using winter grade gas, not the stuff you bought last September. Anyone ever run any ethanol mix (max 10%) in a chain saw? The stuff has its anti icing built in; my truck always ran well on it.

 

[Crofter]

Carb Icing

The worst temperature is a few degrees either side of freezing with high humidity. Filter blocking with snow is a different thing and usually worse at cold powder snow conditions.
I remember seeing something in the instructions on a friends ultralight plane with a Rotax 2 stroke not reccomending fuel with alcohol in it as it interferes with the fuels abilty to keep the oil mix in suspension while sitting unused. Modern premixes thoug must be used to living with ethanol and metanol, Mtbe, and whatever all is in todays pump juice.

Frank

 

[Fish]

Must have been using premium.....

Regular gas does not ice up the carb, because of all of the heat
from pinging and predetonation.


Seriously, the scenario you put forth does not mean the problem
was "carb icing"

Maybe water in the fuel froze, but that is not the same as
"carb icing". You already have the boys breaking out the books
to work on their thesis's on the topic. Carb icing occurs at
temps well above freezing as well, it involves physics, and stuff
that the next several posts will go on about thoroughly.
You may see big words, so be warned.

 

[stihltech]

icing

A lot of saws have a door in the shroud that can be opened to let some heat from the cylinder be directed into the carburetor area to stop icing. I also put just a small of isopropyl drygas (the only kind I will use) in the fuel. If I work on a saw and find water in the tank, I put a little in the tank. No adverse effects so far, but I do try to use small amounts as the bottle says it will treat 16 gallons.

 

[eyolf]

I have indirectly experienced the symptoms you're talking about, cutting with another fellow in cold weather. His situation was keeping the saw, and his gas in a heated garage. Condensation in tank, and probably gasohol: we took the carb apart and found the inlet screen plum full of ice crystals.

This was on a Homelite reed valve saw with no provision for carb heating from the engine. We cleaned the screen, and used clean gas from my can for the rest of the day, didn't have no more trouble.

I suppose what might have been happening was that the alky had absorbed about as much water as it was able to. When the water-logged gas reached the carb (and carbs run cool because the evaporating gas robs heat) some of the water started freezing up.

I don't think using gasohol in a chainsaw is a good idea, especially if you're the type that mixes up a can of gas in July and can't use it up until December. I don't like using isopropyl alky in two-stroke gas, but if you must do it, don't mistake HEET, with wood (methyl) alky in it for the good stuff. Heet softens diaghragms and causes more trouble. The best bet is trying real hard to have fresh, clean, dry gas. If you have to, buy premium to get away from the gasohol.


How's that, Fish...only a few big words like Homelite, gasohol, diaghragm?

 

[Gypo Logger]

What happens with carb icing, is that the ambient temp. fluctates with the lower octane, causing demistification of the molecular structure of the inherant components of the fuel.
This in turn, causes frapulation of the timing and actually retards detonation, so the ice cyrstals lodge themselves in the venturi, thus reducing laminar flow, much life taking a piss at 45 below zero, or something like that I guess.
John

 

[Fish]

John,
Wouldn't the glow from the melting piston from the low octane,melt the ice?
Even though the drop in air pressure at the venturi would tend
to further cool the vapor, that could be compensated by removal
of the compression release. If then you could get the saw to run
backwards, and put your weed on the muffler screen, you
could have a power, Swedish {or German} bong. But I digress,
I should have posted this on the saw running backwards thread.
What are your thoughts on this Dr. Lambert? Proffessor
Babcock probably would have some good insight in this area as
well.

 

[Gypo Logger]

Hi Fish the air fuel mix as it flows into the combustion chamber is not perfectly atomized, that is the fuel vapor droplets consist of larger droplets of fuel molecules surrounded by air. It takes additional energy to further atomize this vapor in order to cause carb icing, that is to break the hydrostatic forces (the surface tension of the fuel droplet). This additional energy can be taken from a hot surface (such as a makeshift bong or the piston crown, etc.), which then leads to a cooling of the piston causing carb icing. The additional energy can also be imparted via large turbulences and pressure waves, as in a squish band-type motor, which will help to further atomize the fuel reducing the refrigerant factor. Note that the term "atomize" is actually misleading since the molecules are still left intact, that is the hydrocarbon chains (and oxygen bonds for alcohols) are not broken.
John

 

[Crofter]

Gypo, are fuels containing alcohol blends more or lesss prone to carburetor icing than non blended gasoline?

Frank

 

[Harley]

I had a frapulation incident the other day. Man talk about a bad day, with the fraping and the deatomizing. I couldn't get a ???? thing done.

Fish, I almost fell outta my chair when I read about the swedish motor bong. I know some people who would pay money to see that.

 

[John Ellison]

Seriously, what do you do when your Swedish motor bong starts to frapulate? OR worse yet atomize?

 

[GASoline71]

Dood... you drunk??? This thread is almost 4 years old!opcorn: opcorn: opcorn:

Gary

 

[John Ellison]

Its a humorous thing, you'll never understand.

 

[Lakeside53]

What happens when a bong frapulates?

 

[stihltech]

bong

It is not pretty.:help: And stand back!:jawdrop: