Sam R
8mm Socket
Hey folks,
I've got a 391 in the shop right now with the complaint of non-running. When the owner brought it in I tried a couple things to see if there was a simple-ish fix, since he claimed it ran fine a month prior.
Today I started the diagnosis, but between 2 jobs and working about 14 hours today I just kind of ran out of steam - plus there's a good amount of getting into it with that carb, boot madness setup. It's been trimmer week at work and I've been spoiled on super easy-to-work-on tools. But I digress...
When I put the ZAT4 on it, it actually fired right up. It ran a little rough, kind of sounded like it wanted to die, but didn't. And smoked on WOT. Arrester not present, muffler very clean.
Sort of sounds like old gas or maybe crud in the carb/fuel lines. Fuel line passed spec, the gas did too. One of those little chemical swabs that say if it's good, stale, bad.
For those familiar with Stihl's engine check, I got as far as p/v test - it failed v pretty badly, passed p. I think I maybe didn't have it set up quite right, those boots always seem to give me trouble.
Anyway, my question is that it - if I'm using my nomenclature right - is a stratified carb, I was wondering if anyone has experience with these being a PITA, bitchy, not wanting to work right, etc. I did not do any inspection on the carb beyond visual. Didn't take covers off or pressure test the inlet needle.
I'm sure I'm forgetting something but just ask, I probably did what you'll suggest. But I'd like to hear what folks might think or if someone is going to say the 391 is a diva saw.
Anyway, thanks for reading and your input. Officially I'm not stumped I'm just looking for second opinions.
I've got a 391 in the shop right now with the complaint of non-running. When the owner brought it in I tried a couple things to see if there was a simple-ish fix, since he claimed it ran fine a month prior.
Today I started the diagnosis, but between 2 jobs and working about 14 hours today I just kind of ran out of steam - plus there's a good amount of getting into it with that carb, boot madness setup. It's been trimmer week at work and I've been spoiled on super easy-to-work-on tools. But I digress...
When I put the ZAT4 on it, it actually fired right up. It ran a little rough, kind of sounded like it wanted to die, but didn't. And smoked on WOT. Arrester not present, muffler very clean.
Sort of sounds like old gas or maybe crud in the carb/fuel lines. Fuel line passed spec, the gas did too. One of those little chemical swabs that say if it's good, stale, bad.
For those familiar with Stihl's engine check, I got as far as p/v test - it failed v pretty badly, passed p. I think I maybe didn't have it set up quite right, those boots always seem to give me trouble.
Anyway, my question is that it - if I'm using my nomenclature right - is a stratified carb, I was wondering if anyone has experience with these being a PITA, bitchy, not wanting to work right, etc. I did not do any inspection on the carb beyond visual. Didn't take covers off or pressure test the inlet needle.
I'm sure I'm forgetting something but just ask, I probably did what you'll suggest. But I'd like to hear what folks might think or if someone is going to say the 391 is a diva saw.
Anyway, thanks for reading and your input. Officially I'm not stumped I'm just looking for second opinions.
