MS200T - Boiling Fuel

TreeLogic

TreeLogic

Branched out member
Location
Coastal SC
A couple of times now I've run the 200 a little hard before grabbing a bigger saw. It shuts off early. I go to check the fuel, open the cap, and get 2-cycle gas spewing in my face. Not cool.

After my eyes stop burning, I check the tank and the gas is literally bubbling (looks like it's boiling) inside.

What gives? The saw otherwise performs great.
 
[ QUOTE ]
A couple of times now I've run the 200 a little hard before grabbing a bigger saw. It shuts off early. I go to check the fuel, open the cap, and get a 2-cycle facial from gas spewing in my face. Not cool.

After my eyes stop burning, I check the tank and the gas is literally bubbling (looks like it's boiling) inside.

What gives? The saw otherwise performs great.

[/ QUOTE ]

I am a Stihl fan. I even own a very old Stihl shop vacuum.

Over the years I’ve had a few problems w/ the tank vent caps.
I replace the cap on a back-pack BR300 about every 3-4 years. It stops venting.
If the tank is over half full, it spits gas out and onto my back.

However, I don’t see how the cap could cause the gas to “boil”.
If the gas was under vacuum, causing it to “boil”, the boiling should stop instantaneously when the cap is removed ???
 
Greg,
It's a pretty crazy sight. I haven't fixed it yet so I'll see if I can't reproduce and get a video. We're in the middle of our 2nd ice storm of the year so today looks like a good day to mess around with it.
 
I'm not saying that it doesn't boil.
I just don't see how the cap could cause it AFTER the cap is removed.

My problem is pressure buildup; this would inhibit "boiling".

Do you have another saw with the same cap ? Just switch them, & keep looking for the cause. :-)
 
I've had the famed fuel exploding into my face, usually in hot weathe. II'd attribute it to pressure in the tank. Saw usually stalls, which prompts me to check the fuel level, followed by gas all over me. Good times when it's 95 out.
 
This actually sounds very dangerous.

If it really is boiling the vapors will be higher concentration & more flammable than normal............

Just for a tech check I contacted Stihl Tech Service, to double-check about the exhaust/muffler temperatures......

"The temperature COULD be high enough the ignite the fumes"
 
Greg,
I agree. If it was a pressure thing, it should stop pretty quickly once the cap is removed.

I'm thinking possibly a combination of "winter setting", clogged tank vent, and hot muffler may actually be heating the gas to boiling point... which I'd assume is way less than water's.

If so, the fumes would be ready to ignite and you could have a flame thrower in your face. I'll make sure to take precautions next time but honestly it sneaks up on ya. You think you're out of fuel and then you get a rude awakening. Hopefully we find out more.

Thanks for checking in to it.
 
I just had a similar ‘sounding’ experience for the first time in 35 years of running one model of saw. If there is any chance you put on a new type of fuel line I might have a little more info..
 
No. Only mod was changing from summer to winter setting. But I think it happened on summer setting too.

Haven't messed with the fuel line, though I suppose any info would be helpful. Thanks
 
As I said first time experiencing this in 35 years. Not sure it is this but I had just installed a new Tygon LP 1100 fuel line that is resistant to ethanol up to 100%. It is a laminate of two different materials and as I was installing it it pulled through the fuel tank hole a little hard and instead of removing it and applying grease I just pulled harder and stretched it some. Second saw instal I used a little bit of grease and it was still a little too tight so I pulled on it harder than I will in the future.

After I had the ‘boil’ over or pressurized fuel come bubbling out of the tank I wasn’t sure which saw I had pulled on harder etc.. Haven’t reused those power heads of late and not positive that it will reoccur but, I was wondering if the fuel line was somehow bleeding pressure into the fuel tank between the two laminates.

Sounds like you are off to deal with other issues.
 
Man, that was a real geyser. I've never experienced this so I thought maybe what you guys were describing was just a mist that sprayed out. Nope! That could be a serious problem, as others have noted. Not cool at all to be hanging from a rope at 50 feet, suddenly covered in gas and holding a saw with a blazing hot muffler. What a potential nightmare.

"Winter setting"- is that a switch under the carb cover? I'm guessing it adjusts air intake?
 
[ QUOTE ]
"Winter setting"- is that a switch under the carb cover? I'm guessing it adjusts air intake?

[/ QUOTE ]

Does the 200T have this setting option?
My 020T does not.
My 044 does have that option.
 
Winter setting: pull black metal piece by hi/lo carb settings, place window side down, reinsert, and tighten screw. Allows more air flow into the mix I assume.

FWIW: Tank vent was pretty caked up with debris. Cleaned it, washed air filter, soldered on broken "off" switch connection (different issue but proud of myself), adjusted idle speed, hi/lo, and seems to be running perfect, in the shop at least.

Will run it a little harder here shortly, try to reproduce the issue, and report back.
 
You must log in or register to reply here.

New threads New posts

Back
Top Bottom