Stihl 362 Overheated Today, Boiling Fuel?

[navistar82]

I was finishing cutting off some stumps today, bout 20" diameter. Its been hot here in Indiana for a while now, 96 degrees today. Now, I cut one stump off at the ground, shut it off to adjust the chain and grab some more oil and fuel from the garage. The saw was sitting in the sun for maybe 5 minutes.

I went to restart it and it wouldn't start, It would act like it was gonna run then die. I hadn't topped it off the tank yet so I checked it. Took the cap off and the fuel was boiling out, spraying everywhere.

I run 89 octane with Stihl 50:1 synthetic oil. Ive read a couple places to change to 40:1 to keep this from happening. Said 50:1 is more of a EPA thing than good for the engine.

Is this normal on hot days? Ive never cut on days this hot, but the heat isn't letting up here and I had to get them cut down.

Thanks

 

[CTYank]

I was finishing cutting off some stumps today, bout 20" diameter. Its been hot here in Indiana for a while now, 96 degrees today. Now, I cut one stump off at the ground, shut it off to adjust the chain and grab some more oil and fuel from the garage. The saw was sitting in the sun for maybe 5 minutes.

I went to restart it and it wouldn't start, It would act like it was gonna run then die. I hadn't topped it off the tank yet so I checked it. Took the cap off and the fuel was boiling out, spraying everywhere.

I run 89 octane with Stihl 50:1 synthetic oil. Ive read a couple places to change to 40:1 to keep this from happening. Said 50:1 is more of a EPA thing than good for the engine.

Is this normal on hot days? Ive never cut on days this hot, but the heat isn't letting up here and I had to get them cut down.

Thanks

Fuel to oil ratio irrelevant here. No substance to speculations.
Two major possibilities: metal tank heated by engine or sun; winter-blend fuel (more light-ends than summer blend.) How you gonna put that on EPA?

 

[navistar82]

First off 362's have plactic tanks, second, I didnt put anything on the EPA, it was actually off this forum where I read it. Here is the link for it.

http://www.arboristsite.com/chainsaw/26511.htm

 

[Anthony_Va.]

You're fuel can boil when it gets really hot and you're running the saw quite hard. Just try to keep it sitting in the shade and shut it off instead of sitting it down and letting it idle. That what I try to do that seems to help anyways. Running a saw when it's hot can be miserable. But when theres work to be done....

 

[WRW]

Higher octane helped me with that problem.

 

[navistar82]

Ok, thanks guys. Im low on fuel so ill bump up to 93 octane. Is there any truth behind the different fuel/oil ratios from the other post?
Thanks

 

[o8f150]

glad i am running 93 octane since i have a tree to cut up thurs morn and its going to be hot here too

 

[Anthony_Va.]

I've always ran 93 octane and my fuel boils from time to time when its really hot. It may be worse with lower octane but it still does it with 93.

 

[bryanr2]

I run 93 octance no ethanol and mix synthetic 40:1. I have seen fuel boiling but it was in my Johnsered a couple monthes back. I was noodling big rounds so I could move and it was hot. I dont make a living with my saws so I try to limit use on hot hot days.

 

[outdoortype]

Mix ratio not the culprit

Gasoline evaporates, boils, vaporizes etc readily even at normal temps. Then factor in chainsaws run super hot plus hot weather/ambient temps not absorbing the heat from the saw. Next time put your hand near the bottom of the saw where the crankcase meets the tank. Even after sitting in the shade for 10 minutes you'll see what I mean.

 

[WRW]

I've always ran 93 octane and my fuel boils from time to time when its really hot. It may be worse with lower octane but it still does it with 93.

Yeah, I forgot to mention that I also switched to a national brand at the same time. Worked for me, YMMV.

 

[Andyshine77]

Are you sure the fuel was boiling? or was there simply a lot of pressure in the tank? Fuel tanks build pressure and it's normal to hear some fuel vapor released when you open the tank, especially on hot days.

 

[navistar82]

Are you sure the fuel was boiling? or was there simply a lot of pressure in the tank? Fuel tanks build pressure and it's normal to hear some fuel vapor released when you open the tank, especially on hot days.

It sure looked like it was boiling, took the cap off and the fuel blew out of the saw. Fuel in the tank was swirling/bubbling a good 7-10 seconds after removing the cap.

 

[Cliff R]

"Heat soak" more than overheating. I have had the same thing happen a few times on really hot/humid days and working my saws pretty hard. Fine if you fuel them quickly and restart, but letting them sit 10-15 minutes resulted in difficult restarting and acting lean for a half minute or so till they moved some fuel thru them.

I think it's worse with this new fuel, the ethanol ain't helping one bit, as it evaporates and boils pretty easily......Cliff

 

[rob066]

Sometimes when stumping on hot days I dig a trench around a stump with a maddox. I know it is extra work. But it lets the outlet air from the cylinder go somewhere. That atleast it is not tight on the ground building excessive heat.

 

[lone wolf]

Just use two saws so one gets a chance to cool off. if you were cutting stumps I would think the chain would be getting dull causing you to put a lot more pressure on the saw chain causing more heat. Use two saws let one air cool a bit and alternate.

 

[Whitespider]

Back in the 80’s, when there were still a lot of low pressure fuel systems still in service on cars and trucks, the “boiling” of Ethanol blended fuel was a common problem during hot weather, causing vapor lock. The stuff would actually vaporize in carburetor float bowls, fuel lines and engine mounted mechanical fuel pumps. We saw more of it in late spring and early summer, presumably because some winter blended fuel was still being sold… but it could, and would happen any time of year. Even the early low pressure fuel injection systems (CFI) were susceptible to the problem. Commonly the vehicle would “vapor lock” while idling, such as sitting at a stop light, and it wouldn’t restart until the engine compartment was allowed to cool for an hour or so… but it could, and would happen while driving down the road, especially with large V8 engines.

I don’t know about Indiana, but ‘round here 89 octane fuels equate to 10% Ethanol blend… and I avoid it like the plague. The 87 octane stuff is (usually) Ethanol free, but it’s crappy gas for a two-cycle engine. Near all the 90/91 octane fuel is Ethanol free, but the 92/93 octane stuff is more often another 10% Ethanol blend. In Iowa, any fuel containing 1% or more Ethanol must be labeled on the pump, so it’s relatively easy to spot the Ethanol blended fuels as you drive by the pump (big green label that says “Contains Ethanol – Cleaner Air For Iowa”… what a friggin’ joke!).

Just sayin’.

 

[Trailtrimmer]

As soon as you shut off a saw, air stops moving through it. All the heat in the engine just soaks the fuel tank and if you were just running it hard then it's going to be hot.

While it may sound bassackwards, let it idle for half a minute to a minute before shutting it down so air gets pulled across the fins and block and cools it. Also, fill it quickly rather than waiting for the tank to get fully heat soaked or plan on waiting a long while before cracking the cap open.

 

[navistar82]

I don’t know about Indiana, but ‘round here 89 octane fuels equate to 10% Ethanol blend… and I avoid it like the plague. The 87 octane stuff is (usually) Ethanol free, but it’s crappy gas for a two-cycle engine. Near all the 90/91 octane fuel is Ethanol free, but the 92/93 octane stuff is more often another 10% Ethanol blend. In Iowa, any fuel containing 1% or more Ethanol must be labeled on the pump, so it’s relatively easy to spot the Ethanol blended fuels as you drive by the pump (big green label that says “Contains Ethanol – Cleaner Air For Iowa”… what a friggin’ joke!).

Just sayin’.

Our pumps say 10% ethanol. But it isnt labled per fuel, just one small label on the pump. So there isnt a way of knowing which has it, unless I ask the attendant. Do those additives that are "supposed" to remove the ethanol work? Ive seen some little bottles at Lowes and Walmart that claim they remove it from the fuel.

Thanks

 

[Wood Doctor]

More on Ethanol Mix...

I decided to try an experiment. I ran my 361 for 20 minutes on an ethanol mix on a hot day cutting big elm logs (semi-green). The saw started overheating and quit running altogether a few times, so I shut her down and let her cool down. I dumped out the ethanol mix and replaced it with unleaded regular mix.

The saw ran without a hitch the rest of the way. Believe me, it was still hot. The bar let me know that a couple of times. I could probably have fried an egg on it, but the saw kept running.

I also like Lone Wolf's idea of using two saws. Let one give the other a breather, alternating between tanks or even half tanks.