036 Pro won't stay running

[Woody912]

Saw starts on choke and it will stay running if I leave the start trigger locked but as soon as I get on the throttle acts like it is running out of gas and I get maybe one cut out of it before it dies. Saw is 17 yrs old and carb is original, I suspect it needs rebuilt or replaced. Any other thoughts before I start taking things apart. Rebuilt a couple yrs ago with Tecomate parts and local Stihl dealer rebuilt the bottom half about 3 yrs ago. Probably cut about 10 cord of firewood a year with it. Any reliable source for replace carbs?

 

[jeremyc]

First suspect would be a cracked fuel line. Pull the air filter and stress the fuel line outside of the tank and I bet you will find cracks. Also inspect inside the tank.
May be a carb issue but a fuel line is a good place to start and super common.

 

[lawnboy]

Maybe not your exact same problem but I have a older (metal tag) 036 Pro that would start right up and run, rev and cut but wouldn't idle for more than maybe 5 seconds- tops, was very erratic and had a terrible hesitation when you squeezed the throttle. Seemed like it just needed the low side carb screw opened up, which I did, and it helped, but still wasn't right. Carb had limit caps so I removed those to allow me to open the low side up some more. Saw got better but still was not right. I rebuilt the carb. Same Issue. I decided to just go with a new OE carb. I went ahead and removed the limit caps before installing it. I also replace the fuel and impulse hoses while I was there.
Approximately $100 and however long it took me, lo and behold-same issue. Funny thing is this saw would start just as easy as any perfectly good running saw which was steering me away from it having an air leak. So after a bunch of scratching my head I decided it was time to dig a little deeper-
So I take the saw apart and do a visual on the piston/cylinder/rings, check ring end gap, all of the normal stuff. I check the armature air gap, intake manifold, crank seals, plug wire and pretty much everything I can think of that could be causing this idle/hesitation problem. I am finding nothing obvious.
By now it's time to visit the beer fridge. As I am standing there enjoying my refreshing frosty beverage I just happen to notice something quite odd. On the clutch side of the crankcase where the case is machined for the cylinder base gasket there is a piece of the base gasket approximately 1/4" long dead center in between the front and rear cylinder mounting bolts that is non existent. I probably would have noticed it sooner but it wasn't like it was torn or upset in any way it was just as if it progressively went away over time. Needless to say-That was the problem. New base gasket, cleaned up the cylinder and fitted a new set of rings since I was there and even put the old carb back on. That was over a year ago. Saw hasn't had one single issue since. I just had to tell this one because it is probably as UN-COMMON as they come. You just never know what you will find.

 

[Woody912]

Saw will run a full tank of gas if I never disengage the trigger lock after starting so I am thinking fuel line is OK. Don't have a base gasket anymore but the sealant could have deteriorated. Dishes done so time to start turning wrenches!

 

[lawnboy]

Will it idle??

 

[ELECT6845]

Junk carbs and bad crank seals are what kill these saws. The last 4 I have done all had leaking cranks seals. The other issue is the carbs, if they do start and run if you hold them wot they will rev out to 15,000 + rpms even without an air leak.

If you want it pressure/vac tested bring it to me in Mooresville and I will do it. I also have seals and another carb if needed.

 

[Woody912]

Will it idle??

Today it will idle, run, sit down in the cut and grunt. Might even run to the truck if I whistle for it. Only thing I did was twist all of the needles back and forth several times and then put them back where they were. Some days this saw may be like me, old and canterkerous!!!

 

[Woody912]

Junk carbs and bad crank seals are what kill these saws. The last 4 I have done all had leaking cranks seals. The other issue is the carbs, if they do start and run if you hold them wot they will rev out to 15,000 + rpms even without an air leak.

If you want it pressure/vac tested bring it to me in Mooresville and I will do it. I also have seals and another carb if needed.

Thank you, gonna run it for a few days and see what happens. Had to make about 4 round trips to Mooresville a few yrs back over a trolling motor that was repaired wrong, can't say I enjoy that drive very much.

 

[Woody912]

Thank you, gonna run it for a few days and see what happens. Had to make about 4 round trips to Mooresville a few yrs back over a trolling motor that was repaired wrong, can't say I enjoy that drive very much.

OK, this afternoon it won't run. Stay tuned, I'll figure it out eventually. And I have a new fuel line in the truck

 

[ELECT6845]

It’s going to cook. You got an air leak.

 

[Woody912]

It’s going to cook. You got an air leak.

I do not disagree but why will it run an entire tank of gas on half throttle and why did it run fine this morning??????????

 

[ELECT6845]

Air does funny things. You should get it fixed before it melts down and really gets expensive.

 

[Woody912]

Found problem, impulse line had come off. Really do not understand how it started everytime unless it was tank pressure

 

[HarleyT]

You need to go through the carb correctly, and replace your fuel and impulse lines first off, will probably cure your problems. Do not continue to run your saw until it is fixed, or you will damage your piston.
You ought to go ahead and take off the muffler and peek at the piston now, to see what you have.

 

[Woody912]

You need to go through the carb correctly, and replace your fuel and impulse lines first off, will probably cure your problems. Do not continue to run your saw until it is fixed, or you will damage your piston.
You ought to go ahead and take off the muffler and peek at the piston now, to see what you have.

Replaced that impulse line a year ago. Questioning whether dealer gave me real impulse line or just what he had. Came off the barb too easily