Stihl MS 192T Top Handle Saw

[Wood Doctor]

Have you tried removing the fuel line and blowing it out with compressed air? My one had a little debris in it that caused the primer bulb to not receive fuel, just as you state. Don't blow debris back into the tank!!!! Remove the fuel line from the tank if you can, just a rubber grommet and blow from the primer bulb holes towards the other end. Make sure all other ends of the line are disconnected if you can.

I will try that again. I did exactly that for the 192t and it worked for awhile. I may not have got all of it out or more grime arrived somehow. I'll also remove the carb and give it a good overnight fuel soak.

I think both the pipe #7 and the fuel hose #4 are both potential culprits. I'll also remove the handle housing to make it easier to operate on them. The hardest line to remove and reinstall is the tank intake #2.

 

[singinwoodwackr]

I will try that again. I did exactly that for the 192t and it worked for awhile. I may not have got all of it out or more grime arrived somehow. I'll also remove the carb and give it a good overnight fuel soak.
View attachment 1206652
I think both the pipe #7 and the fuel hose #4 are both potential culprits. I'll also remove the handle housing to make it easier to operate on them. The hardest line to remove and reinstall is the tank intake #2.

Check the tank vent and line as well

 

[Wood Doctor]

Check the tank vent and line as well.

I've done all that as well. including the line elbows. I even removed the carb and connected up dummy Tygon fuel lines to it along with part #6, all connected to a jar of fuel. It pumps fine then and fills the primer bulb, all the lines, and pulls fuel through the carb. But, when I reinstall part #6 and Stihl's checked-over lines, no fuel makes it to the bulb from the tank and the saw is a dead puppy. All three of these Stihl top handle saws do the same thing. I have never had this happen with either Echo or Husqvarna.

I have considered replacing all of these checked-over Stihl fuel lines with Tygon tubing and part #6 and see if I get the same result. Sounds goofy, but nothing else is working.

Maybe the Bermuda triangle was blown 2000 miles northwest to Nebraska.

 

[singinwoodwackr]

I've done all that as well. including the line elbows. I even removed the carb and connected up dummy Tygon fuel lines to it along with part #6, all connected to a jar of fuel. It pumps fine then and fills the primer bulb, all the lines, and pulls fuel through the carb. But, when I reinstall part #6 and Stihl's checked-over lines, no fuel makes it to the bulb from the tank and the saw is a dead puppy. All three of these Stihl top handle saws do the same thing. I have never had this happen with either Echo or Husqvarna.

I have considered replacing all of these checked-over Stihl fuel lines with Tygon tubing and part #6 and see if I get the same result. Sounds goofy, but nothing else is working.

Maybe the Bermuda triangle was blown 2000 miles northwest to Nebraska.

Try reversing the lines to the bulb?
Man, you got a weird one.
Eventually it will turn out to be something stupid simple

 

[Wood Doctor]

Try reversing the lines to the bulb?
Man, you got a weird one.
Eventually it will turn out to be something stupid simple

Tried reversing them last week, just in case I somehow had part #6 upside down (a virtually impossible act). The longer nipple goes below the shorter one. The shorter one connects to the carb and pulls fuel into the bulb as it pumps. Yes, this is a weird one. especially since three saws the same age all have the same symptoms. I'm surprised you have not run into this with your 193T, and I have serviced a half dozen or more Stihl top handle saws in the past three years and never experienced this.

These three saws were dirty from cutting and appeared to have just stopped dead while in action and could not be restarted by any saw operator on the team and me. So, they decided to ask me for help. I think the Tygon lines idea, replacing parts 4 and 7 is worth a try. I have a good supply of it on hand.

 

[lone wolf]

I will try that again. I did exactly that for the 192t and it worked for awhile. I may not have got all of it out or more grime arrived somehow. I'll also remove the carb and give it a good overnight fuel soak.
View attachment 1206652
I think both the pipe #7 and the fuel hose #4 are both potential culprits. I'll also remove the handle housing to make it easier to operate on them. The hardest line to remove and reinstall is the tank intake #2.

Is the fuel line real soft ?

 

[Wood Doctor]

Is the fuel line real soft ?

Somewhat. but not too flimsy. I removed the fuel intake line today (not easy) and checked for leaks. None existed. But, the connection to the carb's nipple may not be as tight as it should be. That's why I'm suggesting a temporary Tygon replacement for it.

 

[lone wolf]

Somewhat. but not too flimsy. I removed the fuel intake line today (not easy) and checked for leaks. None existed. But, the connection to the carb's nipple may not be as tight as it should be. That's why I'm suggesting a temporary Tygon replacement for it.

Tygon stinks, but it may work for a test.

 

[stihltech]

Diagnose the system. Does the primer itself work? Can you put a vacuum on the suction side of the pump and draw fuel? Does the outlet side of the pump make pressure? Is the supply side of the carburetor leaking anywhere? Is the return side open to the tank. Is the tank vent opening. If all this checks, it is back to the check valves inside the carburetor.

 

[Wood Doctor]

Diagnose the system. Does the primer itself work? Can you put a vacuum on the suction side of the pump and draw fuel? Does the outlet side of the pump make pressure? Is the supply side of the carburetor leaking anywhere? Is the return side open to the tank. Is the tank vent opening. If all this checks, it is back to the check valves inside the carburetor.

All of the above I believe are OK except the supply side of the carb that connects to the intake fuel line could be leaking as the primer is pressed. That is why I want to connect a Tygon fuel intake line just to be sure the connection is tight to the carb. I can hear air squeaks as the bulb is being pressed repetitively and the bulb never fills up.

The outlet side of the bulb does work. I tried both a new bulb and the OEM with the inlet side connected to a fuel tank with a Tygon hose and the outlet to a Tygon discharge line. The bulb filled up and so did both the inlet and outlet line.

I would like to think that the check valves inside the carb are the problem, but I have tried two new carbs in addition to the saw's original carb. Fuel makes it through any of them and back to the primer bulb whenever I use a temporary fuel line hookup with the carb removed but connected.

About the only thing I have not done is to connect an installed carb's fuel intake nipple to a temporary Tygon fuel intake line that reaches back to the tank. I hate doing that because the more I disconnect the OEM intake line (part #4). the more it could be damaged and set up a leak with the carb's nipple. Regardless, that is my next step. As Lone Wolf said "Tygon stinks, but it may work for a test." I agree because I believe that parts #2, #3, #6, and #7 all work fine based on what I did today.

 

[singinwoodwackr]

"Vajankle" ... today I learned a new word!
I can hear air squeaks as the bulb is being pressed repetitively and the bulb never fills up.

Then you have a definite air leak somewhere in the lines or at a line connection. Remove all lines, including impulse and do pressure tests.
Then, do as you suggest, hook up a known good line to each and every connection and pressure test with soapy water spray.

 

[singinwoodwackr]

Waiting on fuel lines and 1 boot. Hope to God I don't catch your bug

 

[sean donato]

Last time I had similar issues, I replaced every last fuel line in the stupid thing. They are a pain to work on and fuel lines are cheap enough not to want the hassle of dealing with old lines. It should take basically no effort to pull fuel through the carb via the purge bulb or with a mity vac hooked up. Stupid things are way over complicated for what they do. If everything fuel line checks out, the impulse would be suspect. Crank seals and the crank case like to leak too. All verrificable with a pressure/ vac test like mentioned above.

 

[Wood Doctor]

Beautiful Pics in post #32 by the Singing Woodwacker. I like to sing also but these top handle saws are a PITA and force me to sing off key. I can see why so many wind up in the bone pile, ready to be parted out.

I succeeded in replacing both lines with Tygon, but only the fuel intake line was probably necessary for a diagnosis. One of the carbs was bad and refused to co-operate and allow fuel to fil the intake fuel line. I replaced that carb with a new one and it allowed the intake line to fill but still had no luck. Even with a partially-filled bulb, the saw would not even try to run. I'm now convinced there are more serious problems, such as a case crack or insufficient compression (or both).

BTW, I did figure out how to attach the lines without having to remove the outer handle. The pipe can slide underneath the handle and come in from the side. It's tricky but allows connecting to the boot.

 

[singinwoodwackr]

Pull the motor and inspect it, pressure test it.

 

[singinwoodwackr]

Have you pulled the intake boot and inspected it for cracks?
One of these 2 I have gets a replacement boot…sm crack.

 

[cookies]

On those little gremlins I tear them all the way down, too many issues with the intake boot and impulse mixed with people using go juice to make them run when they needed repairs.

 

[Sidecarflip]

Last time I had similar issues, I replaced every last fuel line in the stupid thing. They are a pain to work on and fuel lines are cheap enough not to want the hassle of dealing with old lines. It should take basically no effort to pull fuel through the carb via the purge bulb or with a mity vac hooked up. Stupid things are way over complicated for what they do. If everything fuel line checks out, the impulse would be suspect. Crank seals and the crank case like to leak too. All verrificable with a pressure/ vac test like mentioned above.

Been my experience that no 'machine' of any type is 'stupid', they just do what the human inputs to it so IMO, the stupid part lies with the operator... Not trying to demean you, just stating a fact.

 

[sean donato]

Been my experience that no 'machine' of any type is 'stupid', they just do what the human inputs to it so IMO, the stupid part lies with the operator... Not trying to demean you, just stating a fact.

Designer(s) were stupid in this case. Not the operator nor the mechanic fixing it. Besides that, it's an inanimate object, ie stupid.

 

[stihltech]

This is why my first line of defense is a visual inspection and then a vacuum and pressure test of the motor and fuel system. Without that, you are just guessing.