Free saw (doesn’t start) any tips?

picked this up on the neighborhood Listserv. I was hoping it would be the ole chain brake engaged issue, but he said he had 4 others and had quite some stacks of wood himself, so now I’m thinking it was a fuel issue especially because this and a 1 season old weed walker both wouldn’t crank.
I haven’t even tried cranking it yet. Any pointers before I do? Or resources for troubleshooting?

 

Drain gas and put in fresh mixed oil/gas, see if it'll chug at least.

Check/change plug

It could be a carb issue if gas has been left for a while.

Worst case scenario, pull muffler and see what cylinder looks like.

Oh, you may be able to "borrow" (deposit likely required) a compression tester from one of the local auto parts store, that'd be a good start.

 

Went to drain the tank, but it was dry, so put in a couple ounces of “mechanic in a bottle, cranked it a few times and then went to check out the spark plug. Spark plug looks new, but has a ring of whiteish oxidation on it. I already had a replacement, so I squirted some “starting fluid” in the cylinder. No dice, but I haven’t added real fuel mix yet. The thing is, I don’t see a spark when I crank it open with new or old plug on. It’s bright out here in the shade and I don’t know what to look for, but I don’t see a spark. Also there was sawdust on the inside of the air filter.
Is the lack of spark likely meaning a coil replacement is due? I could check for shorts if I do some more disassembly, but this thing is pretty new. Probably coil?
This is my first time in an engine, any help is appreciated.

 

Wait, there must be some kind of spark because it was going for a second there. I tried to pick it up quick to throttle and it cut out.
Then I couldn’t get it going again until I sprayed some more starting fluid in there. Should I let it idle longer? Add real fuel in?

 

Better see why its not getting fuel. Float stuck?

 

It’ll run for a few seconds, whether it is idling or petal to the metal and then it seems to cut out when the starter fluid runs out.

 

carb and fuel line issue- no fuel indicates carb likely has a case of ethanol death. rebuild carb or replace, fuel line and pulse line get hard and crack or depending type of line get all rotted internally- plugging carb, also the filter on end of fuel line in tank could be blocked up from ethanol deposits as well. chainsaws and weed wackers have all position carbs no float there is a diaphragm in them that can be attacked by the ethanol.

 

The lines “look” like they are pretty good shaped and the priming bulb.. I realize there could be something going on in the inside. I see replacement carbs on Amazon.. are any brands more likely to stand up to the evils of ethanol. Does Stihl use more resistant plastics that it’s not a problem?
What do you guys think? Not really worth the hassle? Think I could figure out how to install a replacement carb?

 

Don't use any more starting fluid, there is no oil in it to lubricate the piston or bearings. Dribble a bit of mix down the plug houl or into the carb. I would either put a new carb on it or put a kit in that one then go from there.

 

New aftermarket carb is $15.99 on fleabay...

 

Is any brand better than another? Think I’ll be able to figure out how to replace it? I guess I can look around for a video. And maybe research tuning it with the old one as a model. I see some kits floating around for cheaper too, but that would probably surpass my mechanical (in)ability.

 

I wouldnt rebuild it...101 ways to screw that up, a bit much for your first carb work experience IMO...

 

You can definitely figure out how to replace the carburetor!
Usually the trickiest part is the throttle linkage. Take good pics of what it looks like before you start pulling it apart.

 

ethanol fuel - let sit for a few months- ethanol separates from the petroleum - running unit dry and letting it sit- what little is left converts to a gummy film , additionally because it is hydroscopic it attracts moisture -in that combination it then attacks metals in the from of corrosion- . Ethanol directly attacks plastics by breaking down the chemical structure. Course I don't know squat ain't got no fancy papers that say I do.

 

So would it be better to store full of fuel? I’ll keep an eye out for a non-ethanol pump, but might be tricky to find these days.
I bought a replacement carb, and will let everyone know how’s it goes. And I appreciate the help/input from everyone; I’m fortunate to be a part of this great forum. I think this will be a great first saw for me to mess around with. I might look in to muffler mods and tuning while I’m not too afraid to mess up a free saw.

 

It says “lubricates upper cylinder” on the bottle.. but if you tell me I am running it dry, I will steer clear. Maybe a dribble of the “mechanic in a bottle” and a spritz of the starter would work?

 

Yeah, ether in a gasoline engine is not good...I won't even let our guys have it for the diesels. Lots of people use it, and get away with it, but lots don't too...

 

I use either starting fluid or acetone to clean oil off metal prior to welding if that says anything for "upper cylinder lubricant" let alone for the bottom end.

 

Point taken, I’ll lay off the starter fluid. How about the mechanic in a bottle? If I am using that or fuel mix, how many ml should I shoot for for starting a 37cc engine?

 

I doubt Mechanic in bottle will do anything other than lightening your wallet. It certainly won't fix 2 stiff diaphragms.
First, I'd like to demonstrate saw is worth spending money on.
1. Tbl spoon/1 oz fuel mix (not starter fluid-bad, as said above) in plug hole. Plug back in.
2. Will be floody - pull 10 - 30x.
3. You should get a burp and 2-3 sec fast run.
That tells you have: compression and spark at the right time. Then, fix fuel delivery. As above, just buy a new carb for ~$16.