Need some help with a Stihl 192C

[Kevin in Ohio]

I bought the saw new and have used it a lot. Recently noticed it was down on power so I checked compression and it was at 85. looked through the exhaust port and intake and looked great so I ordered a set of rings and crank seals. I've always used Stihl oil and non ethanol in my saws. Tore it down and piston/bore look great with no scoring to be seen. The problem was one of the bolts that hold the case together was loose and the crank seal on one side was spinning in the housing. It wore it some. No ridges on the outer edge of the seal where the new ones had that. I dry fit it and it was snug so I was hoping it would be okay. I used Dirko like normal, but also put some where the bad seal was. Hoping this would help lock it in position. Put it all back together, let sit for a day. Today I tried and it started right up. My issue is it will not idle and if you let it go to 1/2 throttle, it dies from what I'm guessing is lack of fuel. It will run at full throttle and be real smooth. I've tried adjusting the carb, and put on 2 other carbs I had. Same thing. Had a new one in the box and it goes instantly to full throttle and adjusting won't change it.(must be defective)

Any ideas here? I changed the intake boot about a year ago with an OEM Stihl and ran great after that. Looked it over real good and see no issues there. I looked at the impulse line and fuel hose and they too look fine. When you pull the carb it pours out fuel from the tank. I did change the fuel filter as well. Just kind of frustrated/stumped. I don't have a vaccuum testor for a leakdown but is that something to look to next?

Thanks for any insight.

 

[pioneerguy600]

Vac and pressure test.

 

[cookies]

I like to put sealant on the seals when assembling, you may have received a bad seal or had a lip on a seal fold or even tear if installed dry. As suggested you need to pressure/vac test it

 

[Kevin in Ohio]

Vac and pressure test.

Thanks for the reply. I went and bought a Mityvac vaccuum/pressure tester. Blocked the carb port and exhaust and it holds 7 pounds of pressure with no leak down. Even used soapy water around the seals and no tiny bubbles. Put 7 lbs of vaccuum and it stayed steady as well. Only thing I did notice is my impulse line slips off the hose boss pretty easy. It's the factory one that came with the saw and is a little harder than I thought it should be. I used that to do the testing. I did suck through it and no restriction there. Do you think I should try replacing that or? Since I put a piece of rubber between the carb and intake boot, that rules that out for having a leak.

 

[Tobystihl]

Thanks for the reply. I went and bought a Mityvac vaccuum/pressure tester. Blocked the carb port and exhaust and it holds 7 pounds of pressure with no leak down. Even used soapy water around the seals and no tiny bubbles. Put 7 lbs of vaccuum and it stayed steady as well. Only thing I did notice is my impulse line slips off the hose boss pretty easy. It's the factory one that came with the saw and is a little harder than I thought it should be. I used that to do the testing. I did suck through it and no restriction there. Do you think I should try replacing that or?

Yes!

 

[cookies]

Thanks for the reply. I went and bought a Mityvac vaccuum/pressure tester. Blocked the carb port and exhaust and it holds 7 pounds of pressure with no leak down. Even used soapy water around the seals and no tiny bubbles. Put 7 lbs of vaccuum and it stayed steady as well. Only thing I did notice is my impulse line slips off the hose boss pretty easy. It's the factory one that came with the saw and is a little harder than I thought it should be. I used that to do the testing. I did suck through it and no restriction there. Do you think I should try replacing that or? Since I put a piece of rubber between the carb and intake boot, that rules that out for having a leak.

impulse hose should be a tight fit on both the cylinder and carb, replace it

 

[Kevin in Ohio]

I got a new impulse line and installed that. Holds really good and I did put the original spring back into the new one. Pulled the original carb apart and the diaprahms were a little distorted so I put in both new. Checked the fuel inlet it seats as it should. level checked out okay too. Set the needles to 1 and 3/4 turn. Started it up and adjusted idle to 3000 rpm and full throttle to about 13,000. Had a little stumble off idle so adjusted till that cleared up. It still is not completely smooth. At full throttle it wanders up and down some.

I'm no expert here but what would be the next thing to look for or am I being too picky? Haven't tried sawing yet as I ran out of time, Again, I rechecked and did another vac and pressure test before putting the impulse onto the handle barb(carb mount). It was still okay. I checked the fuel line and it was fine as well as the new fuel filter.

 

[ballisticdoughnut]

Have you looked at the spark screen? I would also pull the fuel filter and pressure test.

 

[cookies]

did you replace the needle while the carb was apart? did you remove the needles and flush out their chambers with spray? did you set the H needle with a fully warmed up saw?

 

[Kevin in Ohio]

Have you looked at the spark screen? I would also pull the fuel filter and pressure test.

Screen was removed when I bought the saw.. I will pull the filter and retest.

 

[Kevin in Ohio]

did you replace the needle while the carb was apart? did you remove the needles and flush out their chambers with spray? did you set the H needle with a fully warmed up saw?

Didn't replace the needle but it sealed so I didn't see the need. Am I wrong? cab was cleaned and reassembled. I was running it quite a bit so I would say it was at operating temp.

 

[Kevin in Ohio]

Is there any possibility of igintion causing fluttering? Ignition is original except for newer plug.

 

[cookies]

Is there any possibility of igintion causing fluttering? Ignition is original except for newer plug.

Needle should be removed and inspected for grooving on the tip, if it has a limited coil it will limit the rpm by stopping spark until rpms drop low enough