Running my chainsaw out of gas "breaks" it

jennigrey · #1 03/21/13, 06:25 PM

I was given a second-hand chainsaw that has turned out to be a lemon. When I run it out of gas, I cannot re-start it. I have taken it to a small engine repair guy in town THREE times. Each time he takes it apart, cleans it, puts it back together and sharpens the chain. Fires right up. But the next time I run it out of gas, I'm up the creek again.

When I'm planning on shelving the saw for a while, I idle it out. I use it until it starts to lean out and the idle kicks up. Once the idle kicks up, I stop using it and let it idle until it runs out.

Later, I re-fuel it and go through the same routine that I do to start it when I first get it back from the shop or between breaks on a job. It seems to flood immediately.

I don't know about the inner workings of a chainsaw carburetor but the guy at the shop said there isn't a float, which makes sense. But the symptoms remind me of a needle valve getting stuck open. I'm guessing that when the idle kicks up as it leans out, something gets stuck open, but I have nothing to substantiate that. Never had this kind of engine apart. I would take it apart myself but I don't have a manual for it, so it would be a project of a caliber that I don't have the time or space on the workbench for.

The guy at the shop has been no help in solving this problem. He blames me. First he said I left gas in it and I said I didn't. Later he said that I used old or bad gas and I said I didn't. Then he said that I must be getting crud in the tank when I refuel. Um, no. Running the saw out of gas costs me twenty bucks plus tax to remedy and NOT running it out isn't an option if it's going to sit for any amount of time. Not going back to that shop again; tired of being blamed (and charged) for his inability to figure this out. I gave him three chances. No more.

Any advice?

Oh, the saw is a Mac 3514.

RonM · #2 03/21/13, 06:37 PM

The easy solution to that problem is dont let it run out of fuel mix......

glenn amolenaar · #3 03/21/13, 06:51 PM

Try putting stabil or seafoam in fuel, do not drain or run tank dry, I use seafoam works great.

primal1 · #4 03/21/13, 07:09 PM

I've always heard you can shelf a chainsaw with gas, just make sure you start it at least once every 2-3 months. We have one at work that is a pain to start again once it runs out of fuel so we just try never to run out

solidwoods · #5 03/21/13, 07:23 PM

Don't run a 2 cycle engine out of gas.
When you do the engine is running for a few seconds with no lubrication.
You are killing your engine,, don't do that.
Any motor shop worth their salt knows that.
jim

arabian knight · #6 03/21/13, 08:45 PM

Yes I will agree don;t let it "run out" 2 cycles engines that hate that. And besides Why "run it out"? Even for storage there are plenty of gas additives to make this a no no for letting something like that run out till next time.

joebill · #7 03/21/13, 09:29 PM

If you are running it out and trying to start it again right off, the problem probably is;

When you unscrew the gas cap, you are releasing pressure on the fuel, and the pressure is the only reason the gas is not boiling. Run it up to regular temp, shut it off and unscrew the cap, you can see the gas boil. At that time, you have vapor instead of gasoline at the carb, and it won;t run.

Filling it when the tank is half empty helps, but it still remains a problem on some saws. Best to leave some fuel in the tank and start it, time to time.....Joe

jennigrey · #8 03/21/13, 10:01 PM

Dagnabbit, that wasn't what I wanted to hear.

Our other chainsaws were never this fussy. We always ran the big ones out at the end of the season to let them sit.

The guy at the shop didn't say boo when I described to him how I let them lean out. He still maintains I'm using the wrong fuel.

I didn't think I'd hurt it letting it idle out. Running it out hard, yes, I can see how that would be bad. But just an idle?

I don't have a problem re-starting it hot with gas in the tank. I've never run it out, refilled it and then tried to start it again hot. I run it out to store it. I had a couple of trees come down early this year so the saw came out of storage only a couple of weeks after I had stored it. That shouldn't be enough time to dry out diaphragms or gaskets or anything.

jennigrey · #9 03/22/13, 03:02 AM

But, having said all that, I'm going to store the saw wet, on y'all's recommendations. Thanks!

Zephaniah · #10 03/22/13, 04:54 AM

Are you sure it "floods" out after you run out?
Are you sure the primer bulb works? the little plastic primer bulb that you push a few times. The Carb works with air pulses from the crankcase to pump fuel. if the gasket leaks or the diaphragm is cracked or fails you have this problem. are you chokeing it corectly when you restart?

gilberte · #11 03/22/13, 05:18 AM

I use one ounce of Seafoam per gallon of gas. I leave gas in the saw when I'm done with it and it might be three or four months before I use it again. My Husqvarna is 12 years old now and I've never had a carburation problem (knocking on wood).

foxtrapper · #12 03/22/13, 05:56 AM

While there is a tiny grain of truth regarding the engine running without lubricant by running it dry, it's a very tiny grain. Honestly, I have never seen an engine show signs of damage from this. The lubricating oil already on the bearing surfaces does not magically disapear when the flow of fuel and oil mist stops.

Really, the practice of running 2-stroke engines dry for storage is a decades old practice. It's old because it works well. Storing one with fuel has long led to sticky carburetors and pumps and such, which makes the restart difficult to impossible without disassembling things to clean them out.

Personally, I suspect you've got two problems going with your scenario.

#1 is the time it takes to get the fuel mixture up from the tank, through the carburetor, and into the engine. This takes a good bit of string pulling.

#2 is flooding it. 2-strokes in general are right touchy about flooding. With chainsaws in particular, the general rule of thumb is choke on until the saw just burps. As soon as it burps, choke off. It will usually start and run on the next pull or two. Leave it running for a few seconds to stabilize itself. And then you're good to go.

**Ross** · #13 03/22/13, 06:34 AM

I dunno we run our saws outa gas all the time. Cool refuel and go. I'd try a different mechanic or a different saw. We run Huskys today but it was true with the Stihls and Poulans too.

Bret4207 · #14 03/22/13, 06:39 AM

Were it me, I'd find a reputable shop to take a look at it. A new fuel filter and check of the fuel lines is the first thing I'd look at. Todays fuels tend to gum up small engine carbs something terrible. A little gum or a collapsing hose can do just what you describe. Slight air leaks in the lines or primer if it has one will do it too.

I personally haven't had any luck whatsoever with Sta-bil. Seafoam does better for me, but running a saw dry usually negates the need for either. If this is one of the consumer level Macs brought out in the past few years, and a quick google search shows it is, you're dealing with a low priced, low quality saw with marginal components to start with.

dkhern · #15 03/22/13, 07:05 AM

i was told the other day that they are now making gas lines for use with ethanol. ethanol breaks the other types down and restricts the flow.

MichaelK! · #16 03/22/13, 08:48 AM

Don't be so worried about taking your saw apart and doing it yourself. It's not like rebuilding a car engine.

After letting my saw sit for a year, it would not start at all. First thing I did was clean the air filter, spark plug, and fresh fuel.

Still wouldn't start.

Next I traced where the fuel lines routed and checked that none were blocked.

Still wouldn't start.

I dismounted the carburetor from the block, split it open and blew carb cleaner through everything. After re-assembly, the saw started, idled few a few seconds, then died. After priming, it would again start, but would instantly die every single time I pressed the throttle lever.

This told me I had two problems. Cleaning out the carb only solved one of them. The saw was stalling because it was not getting enough gas. I blew carb cleaner through the hose and saw it come out the fuel filter, so the filter wasn't clogged. I also cleaned the sintered brass air-vent. The priming bulb was working because I could press it and watch gas squirt. Finally, I read on the internet that it might be that the fuel lines might be cracked.

I replaced all the fuel lines going in and out of the tank, and it started right up. It's now running fine and back at work.

Gennigray, getting back to your problem, I'd start at your fuel tank and follow the path of the fuel every single step of the way till it enters the engine. Just eliminate any potential problem one by one till you get it working. Note that lines in and out of the priming pump might be two different sizes so the inlet and outlet don't get confused.

**Cabin Fever** · #17 03/22/13, 08:56 AM

This won't fix the problem, but next time it happens remove the plug and squirt a bit of fuel mix into the cylinder and see if that doesn't start it up and allow it to keep running.

frankva · #18 03/22/13, 10:14 AM

After it cools.

You don't want to hear it but the key words are "I was given."

Hope you find a quick easy solution.

DaleK · #19 03/22/13, 10:32 AM

I'd find a better mechanic too. I run 5 saws on a regular basis, usually at least three every day, and I run them all dry every fill up and they never get put away with gas in them even overnight. When you have a saw running for half an hour a few seconds without oil isn't an issue.

jennigrey · #20 03/22/13, 11:50 AM

Quote:

Originally Posted by Zephaniah

Are you sure it "floods" out after you run out?
Are you sure the primer bulb works? the little plastic primer bulb that you push a few times. The Carb works with air pulses from the crankcase to pump fuel. if the gasket leaks or the diaphragm is cracked or fails you have this problem. are you chokeing it corectly when you restart?

My method of starting the saw works if I have not let it run out. I don't push the primer bulb at all to start it normally, but I do press it a couple of times after I have run it out and then re-fueled. Just til the bulb is about half-full. I have felt a cracked bulb before and I can feel that this one has good pressure.

After I have run it dry, refilled it, pressed the primer bulb a few times, I go through the same starting sequence I normally use (successfully) before having run it out:
- click kill switch to "run"
- engage trigger interlock
- disengage chain brake
- slide choke out to full
- give one pull (at this point it usually sounds halfway interested in starting)
- slide choke in to half
- pull again
At this point, the saw will start if I hadn't previously run it out. If I had run it out, it doesn't sound at all like it will start. I know that fuel is moving because if I pull on it too many times, the saw starts kicking fuel out of somewhere. The exhaust, I think.