Stihl 1137 impulse fitting plugged solid??

[Stackowood]

Ms192T here. Customer says it starts on choke then dies. After checking all the obvious things I noticed there is zero impulse to the carb. Cracked impulse hose? Not this time!

I can connect pressure or vacuum to the impulse fitting, tried a small hose with compressed air, carb cleaner, etc, and it is plugged solid. It can't be just a little carbon or left over sealant.

Any ideas?

 

[Stackowood]

@TJ the Chainsaw Mechanic : have you ever seen a impulse fitting completely plugged up? MS250 and other models use a very similar fitting, so it's not unique to the MS192T. Thanks.

 

[TJ the Chainsaw Mechanic]

@TJ the Chainsaw Mechanic : have you ever seen a impulse fitting completely plugged up? MS250 and other models use a very similar fitting, so it's not unique to the MS192T. Thanks.

In my short time I haven't yet, you try sticking a small pick in the fitting to see what is in there? Wonder if it's a ton of saw dust. Hose was fine?

 

[Stackowood]

I've tried compressed air, carb cleaner, small wire, and my vac/pressure pump. It's plugged tight. I may have to just split it apart and see what's in there, but the customer probably won't want to get that much $$ into it. Thanks!

 

[TJ the Chainsaw Mechanic]

Yeah, So if you blow some compressed air through the fitting you don't hear Anything air in the crankcase? Plugged tight might be an understatement!

 

[Stackowood]

Yep, time to see if the guy wants to spend some $$ for a complete teardown!

 

[merc_man]

Can you take a small drill bit and spin with fingers to loosen up.

Sent from my SM-J320W8 using Tapatalk

 

[Stackowood]

The fitting makes a tight 90 degree bend, so yes I can get a wire in there most of the way but not a drill bit.

I hooked a hose up to the fitting and filled the hose with carb cleaner. It's been soaking like that for 24 hrs and it is still plugged tight.

 

[Stackowood]

Alright, after a complete teardown here is what I found. The impulse nipple was plugged with a kind of orange powdery stuff similar to Loctite or epoxy. No carbon or Dirko, and the crank, piston, and cyl were clean other than a small amount of carbon on the piston.

I had to use a 90 degree pick to work out the mystery stuff working from inside the cylinder. It was tough to get out.

Any ideas? Does Stihl use some kind of epoxy when they install that little impulse fitting?

Tomorrow it goes back together with new seals and rings! Another 192t saved from the dumpster.

 

[smokepole]

Those 90 deg fittings are just begging to plugged up with something. Get some fine wire like what comes on the card stock parts I.D. tags. That will bend around in the fitting and push through. I take this wire off a tag to use all the time. It also works excellent cleaning out carb passages when rebuilding them. Glad you found the problem.