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running two-cycle out of fuel

B

Bob in SD

Member
Often when I shut off my chainsaw I am not sure if it will sit idle for days or even weeks. In the past I've tried to run it out of fuel each time so there there is not any residual gas to varnish up the carb. Yesterday I was thinking (!) that maybe that's not the best thing for the bottom end. By running the two-cycle out of gas, am I accelerating wear on the bearings? Should I always run it out, never run it out, or quit being so OCD?

Bob
 
I put mine on the shelf after I blow them off and they sit until next time. I have one I dump the oil out if because it will leak everywhere. Other than that, no special care.

If you are using good quality oil it should have the additives to keep it fresh. I swear by Stihl silver jug. I have had to dump all of the gas out after I started it and put new mixed gas in, but the saw had set 9 months or so. I do keep a five gallon can of no alcohol gas to mix for small engines and the tiller - things that don't run through tons of fuel. Everything else gets gas or diesel from the coop delivery truck.
 
my homelite super XL has sat with gas in it all summer all its life, it's over 40 yrs. old,..always starts
 
When you run an engine out of fuel the mixture leans out so much it is like a torch blowing into the combustion chamber for a few seconds. Not good practice to run any engine out of fuel.
 
If its just weeks, you're fine. Multiple months yes run it empty. The oil doesn't get sucked out of the crankcase when you run it dry, it doesn't vaporize like gas.
 
I use the Stihl oil also and run it at twice the recommended rate of oil per gallon. My weed eater can sit all winter and fire up on the old gas left in it.
Richard in NW SC
 
I run Husqvarna oil at the recommended mixture with 1 oz./gallon of Seafoam. Never had gas go bad over the winter and the last 2 cycle carb that I rebuilt was 6 years ago on a used chainsaw I acquired. I do not drain anything or run it out of gas, I just shut off the fuel on the engines that have shutoffs.
 
There are two really good suggestions here. Running something out of fuel means no lubrication for several cycles. When we used to mix fuel and oil for our snowmobiles my dealer told me to get the machine stopped quick if I ever run out of fuel..his rational was that the pistons would be flying up and down for several seconds as the machine slowed down and came to a stop on its own..and all that time there was no lubrication because there was no fuel! Notjustair has it right in my opinion use a fuel stabilizer such as Stihl makes for their saws. It is mixed with the oil in the bottles and ready to go to make your proper fuel ratio. I always buy high test fuel for the chainsaws and trimmers and I use Stihl oil. My chainsaws often sit from one fall to the next, the trimmers from one summer to the next and I never have a problem. Prior to that I used to use Stabil and it gave me the same good results as well. This has been my experience and Stihl recommends using premium fuel in the mixture.
 
I had on old Yamaha 80 dirt bike that I would shut the fuel off so it would run faster for a few seconds the turn it back one. It lasted for years.
 
So, how is running it out gas damaging it. When the gas and oil stop so does the motor. I don't think the brief second or so winding down is going to hurt it.
 
I put Sthil oil mixed with reg. 87 gas with ethanol and add stabil. Saw sits for along time between uses. Running them out of gas will make them run lean which is not good.
 
(quoted from post at 13:44:33 06/06/16) So, how is running it out gas damaging it. When the gas and oil stop so does the motor. I don't think the brief second or so winding down is going to hurt it.
Click to expand...
agree! But on a tangent, what makes a 2~ engine speed up when running out of gas, but NOT a 4~?
 
I never run 2 cycle engines out of fuel . I run 87 octane gasoline with Opti-2 which is said to have a stabilizer. I also use Stratton fuel stabilizer . I have several large saws that don't get used that often and at times set for over a year and start with no problems.
 
You adjust the carb. more rich on a 2 cycle so it does not burn up and lock up when running from being too lean. It is just more noticeable on the 2 cycle because they lean out more and speed up more as they lean out compared to a 4 cycle.
 
(quoted from post at 09:44:35 06/06/16) Often when I shut off my chainsaw I am not sure if it will sit idle for days or even weeks. In the past I've tried to run it out of fuel each time so there there is not any residual gas to varnish up the carb. Yesterday I was thinking (!) that maybe that's not the best thing for the bottom end. By running the two-cycle out of gas, am I accelerating wear on the bearings? Should I always run it out, never run it out, or quit being so OCD?

Bob
Click to expand...

Don't run ethanol-laced 'fuel', non-ethanol costs more around here but it's worth it, in my opinion. :lol:
 
I don't see it hurting it just sitting there idling until it runs out.

What does hurt one is running it under load WHILE it is running out of fuel. That period of time when it is pumping a mix of air and fuel, enough to keep running but a leaner than normal mixture in an already hot motor.

Or, trying to make one run with a partially clogged main jet. Though it isn't running right, to just keep trying to make it run, hoping it will clear out.

I would say, in the long run, running it out is better than leaving fuel in the tank for months at a time. Especially if you run ethanol gas, which is all I can find anymore. Just let it cool some before running it out.
 
I've got around 20 chainsaws at three different locations. I use pump gas with the 10% ethanol because I refuse to pay the extra buck per gallon for "pure" gasoline. Many of my saws sit a year at a time and it has never been an issue. I DO use Stabil. I just got around to selling one of my biggest saws that I could no longer pull the rope on (shoulder is worn out). Why Stihl did not put a compression release on that saw is beyond me. That is my Stihl 045 Super. 87 cc saw from the 80s. Gas was four years old in it which I should NOT of let happen. Regardless, it started right up. I ran it, then dumped new gas in it, and then sold it.
 
Same here with over 16 air cooled engines that get used sparingly . I here all these horror
stories of ethanol , but just has not been the case here. When I pick up one that I know might have been sitting for a while I might dump the old gas and add fresh but not really a problem.
 
I think you're missing the obvious answer. Does your manual specify to run it out of gas if you're not going to use it for a long period of time? And just my two cents, do you run any other equipment out of fuel because you're not going to use it for awhile? Your tractor, quad's, SxS? :D
 
I run a bunch and never run them out. String trimmers etc, set over winter. Snowblower set all summer. I use stabil or sea foam, no problems
 
On my 2 cycle motors I run a good fuel stabilizer and just store them. I often have to dump the fuel out of the tank as it will be stale enough that the Weed eater or chain saw runs bad on start up but they usually will start. Now on the 4 cycle motors If it has shut off and I know it will be setting for months I run the gas out of the carb. Main things like the generator and such. The lawn mowers I just put a heavy mix of Sea Foam in them and some premium gas for over winter storage.

I know many on here seem to not have any issues with ethanol mixed fuel. In my area that is not the case. Motors that are just shut off and let set without any type of stabilizer in them will be gummed up in short periods of time. I have often wondered if the fuel that is mixed with the ethanol here is a real low grade and the ethanol raises the Octane up to meet spec. Then when the ethanol evaporates out what is left will barely burn let alone run in most motors.

I wish we did not have the issues here with the ethanol mixed gas but we do. Even on 2 cycle motors. I now only mix a gallon at a time in the summer. As the weed eater does not sue that much and a larger gas goes stale, even with stabilizers in it, after a 3-4 weeks setting.
 
I have several Stihl chainsaws, use pump gas, TSC(cheap) two cycle oil. Let them sit without running them out of fuel. Last time I had any trouble was back in the 80's just as E10 was coming on the scene. The alky softened and destroyed the fuel lines. Since then they must have changed the material of the lines as I've not had any more trouble since.
 


Those that have never had ethanol problems should count themselves blessed. It DOES happen. I think where you live determines what gas blend you get and that combined with the lube oil is the problem. Doesn't seem to matter if it's a name oil or not, you can have problems. I've seen problems with straight gas too.
 
(quoted from post at 20:29:29 06/06/16) I think you're missing the obvious answer. Does your manual specify to run it out of gas if you're not going to use it for a long period of time? And just my two cents, do you run any other equipment out of fuel because you're not going to use it for awhile? Your tractor, quad's, SxS? :D
Click to expand...
ES! All of them (gasoline , that is, not the diesels :)
 
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