Stihl 193t not idling, only starts on choke

[sgbarnett]

Let me start by saying hello everyone! This is my first post but I’ve began to use these forums quite regularly and learned a ton from you guys.

So I got this pretty used 193t that will only start at full choke and will not idle FOR A SECOND! It also only stays on at about half choke. It is able to rev up at no choke but you have to take it easy on this trigger by kinda pumping it until it gets there. Then when you do get the rpms high, let go of the trigger, it goes dead. You guys get the picture.

It’s got new mix in it, I’ve checked for kinks in the fuel line, and cleaned the carburetor with an air compressor. Anyone got any ideas?

 

[Sam R]

Hi and welcome to AS.
First, by cleaned the carb with an air compressor, do you mean surface cleaning or something else?

Second this kind of issue is probably due to issues with your carburetor or crankcase seals leaking. That being said it'd be a good idea to check everything else to the best of your ability before you go right for resealing the crankcase & replacing the carburetor. I'd say the first place to look would be the fuel delivery system: how does the fuel filter look? What about the spark plug. If both are rotten those could contribute. If you have a mityvac or some kind of pressure/vac tester, test the hoses with pressure to determine if there are leaks. There's a little rubber boot that sits under the carb on this chainsaw that can develop tears. You have to kind of take the intake housing off to really inspect it. Also, check your impulse line - there's a little port on the intake boot that's a much smaller hole that aligns with a small port on the carburetor - this is your impulse line and is essentially what powers your carburetor's fuel pump. The way you can test this if you don't have a mityvac or similar tool is to put a small amount of grease over the hole and pull the starter rope a few times - observe whether the grease moves (in or out are both good) and if they do you have good impulse, if they don't.. that's an issue.

 

[sgbarnett]

I only surface cleaned the carburetor. Can I tell if the fuel filter or spark plug is malfunctioning just by looking at them? Also I should mention that I’m not very mechanically inclined to chainsaws. It’s sort of new to me. I’ve heard a few people mention the impulse line on similar problems.
It’s also worth noting that after I took it all off (carburetor, fuel lines, spark plug), cleaned it, then put it all back together, it idled fine. It would idle without skipping a beat. After a few days of sitting in the shed, I decided to try it out this afternoon. Now back to square 1.

 

[Sam R]

You just look at them: is the spark plug all pitted & black, oily, ash white? If the ceramic collar is a nice brown color that's a good thing. The fuel filter if the element in it is yellow or darker, it's bad.

 

[Sam R]

If any of your replaceables, plug, filters, are doubtful replace them with known good pieces and re-test.