Something stupid I’m missing

[Treeaddict]

Ran the 395 out of gas while cutting in 20* weather. Fueled it and now it won’t fire. Before it died, it ran fast (chain spun on idle) as they normally do when leaning out from little fuel. I’ve never ran that saw out of gas before.

I couldn’t get it fired up again. Pulled 20 times during 3 separate attempts so 60 rips. Choke off (is this proper?)

Any ideas? It’s 2 years old and babied. Hoping it just takes 100 pulls of the ripcord and it’s not in need of repair.

 

[Fiddler]

If the engine had a chance to cool off, I'd have choked it until it at least popped normally.
If you ran it dry, it needs more gas, not air?

Wouldn't vapor-lock under this situation would it?

 

[Treeaddict]

It didn’t have time cool down. Choking restricts airflow but doesn’t affect fuel delivery.

Maybe I sucked debris into the carb? Can it vapor lock?

 

[lxskllr]

Maybe something coincidentally happened to the kill switch. A look tomorrow with fresh eyes may reveal no problem, or a clearer picture of the problem since the saw's basically been reset to zero sitting overnight.

 

[Treeaddict]

Nevermind!!!!! She just fired!! It just needed to sit for a couple hours. I thank God.

I’d still like to know the mechanics involved in that no- start though.

 

[SkwerI]

If you run a saw out of fuel then sometimes you need to choke it once or twice to get it fired again, even if it's still warm. The newer Husqvarnas are bad about that with the new cylinder designs that improve efficiency and emissions.

 

[TINYHULK]

Buckin Billy ray talks in his videos about spraying fuel in the carb to help the old saws prime and get running good. My 395 is ported but the couple times it has ran out of gas I could choke it until pop and start it in idle. The saw never wants to start in choke but if I skip the choking then it doesn’t like to start at all. Not sure what kind of work was done to my carb when it was ported so I’m not sure if it’s different.

 

[Treeaddict]

Matt, none of my Husqys start in choke position. They always pop off and I move the switch to run and then they fire. My top handle trigger will move the switch to run with the trigger so it saves a pull if you’re quick to the draw and depress it as soon as it pops.

My Stihl pole saw and weed eater start while choked and will idle until choke is turned off. I don’t understand why it’s different between brands.

I’ve flooded the 395 by trying to start it with the switch off. Once this is realized, it can be started with the switch on and 10-15 good pulls.

I very rarely run saws out of gas. I just know when it’s time to refuel them. There’s a fear of restarting issues (crap in the carb, long and hard pulling session to prime, etc) that drives that.

 

[SeanKroll]

I've heard a hot saw, likely moreso in hot conditions, running fast and lean when running out of fuel, can have a lean seizure. Dunno.

 

[Treeaddict]

I've heard a hot saw, likely moreso in hot conditions, running fast and lean when running out of fuel, can have a lean seizure. Dunno.

That’s scary. I suppose another reason not to let it run dry

 

[lxskllr]

I'm not sure I've ever run a saw dry. Maybe a brushcutter, but I can't remember. Going lean is one concern, and I've heard Mtronic saws can be a real bitch to start when run dry, so I've always been careful not to let it happen. I keep a run time estimate going in my head, and try to pay attention when it isn't running right(running out of fuel).

 

[SeanKroll]

When you hear it start to rev up, shut it off. Regardless of potential damage, it's easier to restart.

 

[Altissimus]

My two centimes , I run all of my saws out of gas constantly w zero worries ... when topped back up if they don't start (more a warm weather thing) its vapor lock if you leave it for awhile and it does go , if no start (even smell fuel) flooded , let it sit even longer ... the full throttle drop start is a friend here

 

[Burnham]

Another 2 cents worth...only Stihls in my shed.

I try to not run my saws out of fuel, and shut down right now when the low fuel level causes lean high speed. They just are less finicky to restart that way, so easier on me overall. If I do manage to run one empty, I pretty much have made it a rule to set it aside for a while, take a decent break, then refuel it, let it rest a bit more. Usually with that procedure I have no restart issues. Having more than one suitable saw on hand is very helpful in this .

My 5 Stihls, not a one of them from the antique 064 up through the merely elderly 361, will idle under full choke. First pulls on full choke to get a pop, then down to half choke to start. Depends on the temp after that...either immediately move to no choke if above freezing, more or less, or let it warm a bit (that being a few seconds generally) if colder. If really cold, like 15 degrees or less, then it is still as above, but longer idle at half choke before it's ready to run right.

An addition, an edit if you will...the 064 has no half choke position. It's either full or nothing. Took me a bit to figure that out when I first acquired it donkey's years ago and to learn the idiosyncrasies of starting it. Stupid Stihl .

 

[CurSedVoyce]

In your camp B. Try to never let it run out.
I often check my saw in the tree after a while to make sure I can keep cutting. Hate to run out part way through as it becomes a risky situation for those below me or my self while taking a top or dropping logs.
Same with felling. I'll drop a couple and top off before I keep going.
Why run them till dry?
Two of my least favorite things..
Watching a guy go cut stuff first thing in the morning with out topping off his saw.
Hearing the motor getting gunned over and over again while its running out of fuel. I swear. Again, it makes you wonder how some people get through life.

 

[Burnham]

Well it's obvious, Stephen...they manage for the required skills of life by utilizing their sterling backing abilities.

 

[CurSedVoyce]

So, does that mean I must manage them well? By finding some sterling in there to make the day work somehow?

 

[Bermy]

On my felling course it was drilled into us to never start the back cut without making sure you have enough fuel to finish it.
That morphs in time to keeping an eye on fuel levels as things progress, so you never get to a critical stage with insufficient fuel.

 

[SeanKroll]

I heard from Roger that some kid got killed coming under to get the saw that ran out in the back cut, and the piece went, somehow.

As I recall, it was at a place known not to have a culture of safety in WA.

Without being 100% certain, I won't say what company.

 

[stig]

Yet another great thing about the MS500i,
When you run it dry, just refill, press the bulb 8 times to set pressure and it starts at first pull.

 

[sotc]

I've wet the filter with gas and crank with full throttle/ no choke, never fails if not flooded

 

[Trains]

Sounds like when it ran lean and ran out of fuel, you needed to go back to a cold start situation, with choke, so you would draw fuel back up and into the carb.
counter intuitive with a hot saw, but when they lean out and starve for fuel, and wont start with 2-3 pulls warm start, then use choke, and draw up the fuel into the carb again as per a cold start situation.
Just because the saw is at running temp, does not mean that the carb is now automatically full of fuel again.

 

[Al Smith]

What could have happened with a nearly empty gas tank is it sucked up some junk which could get through the filter but plug up the screen in the carb .

 

[Marc-Antoine]

Choking restricts airflow but doesn’t affect fuel delivery.

Yes it does, and dramaticaly. Don't forget that the piston is sucking air like mad all the time. When you chocke, basically, you close the only air intrance (almost), but the piston still want to sip as much as before. The air isn't allowed to go in, so the pressure inside drops severely. The gas is sucked in the carb by the depression through the jets like in a straw. Two consequences: that gives a bigger amount of gas than the one delivered by the ventury effect alone (helps the cold start), but that sucks too the air or the gas vapor occupying the fuel compartment of the carb after running out of gas, so the carb comes back in working condition again with liquid fuel (as it's designed).
That's why I rarely use the decompressor valve on the big saws. Harder to pull yes, but way more effective to replenish the carb with the gas. The engine looses a big part of the depression by the valve, so it has a hard time to suck up the gas to fill the carb. The 3120XP is a bitch to start if you want to play it softly !

Oh! by the way, the vapor lock appears when the carb is too hot and makes the gas boils inside it. The carb can't work because it's full of vapor instead of liquid (in the appropriate compartment), and every time that you manage to suck in the liquid fuel, it vaporises immediately and leaves you only with vapor, which doesn't work to run the engine. It's like the carb is constantly starving of gas, even if there's plenty in the tank.

 

[Nutball]

It didn’t have time cool down. Choking restricts airflow but doesn’t affect fuel delivery.

Maybe I sucked debris into the carb? Can it vapor lock?

Choking can affect fuel delivery since there is less pressure in the intake, which will pull harder on the fuel. Running hard out of gas doesn't give the engine time to cool down. At idle there's still air flowing to cool the engine, but shut it off hot, and the high temp heat slowly radiates out and vaporizes the gas in the carb and fuel line causing vapor lock. Pouring a bit of gas on the air filter can help get it going sooner, just don't put too much on. I now instinctively pull the choke on a saw that's about to dies from running out of gas. It does 2 things: helps it keep running longer so it can cool down, and primes it for a restart. The chances of flooding it this way are low since it is out of gas.