I’ve never asked for help much, I’m the guy that likes to figure things out but I’m lost on this one. I have a Stihl MS362 that I’m having trouble with the carburetor. It was running rough so I decided to do a thorough cleaning on it. In doing so I removed the carburetor and checked though it and didn’t see any visible debris, no varnishing. The diaphragm was a little bit stiff but I put it all back together. The saw cranked on the 2nd or 3rd pull but would not idle but instead the engine raced away at full throttle without pressing the throttle. I immediately shut the engine down. I tried messing with the high and low idle jets and the idle set screw. Same issue. Now I have the idle set screws all out of wack. Any help would be greatly appreciated.
Stihl MS362 Carb Issue
- Thread starter ChickenPappy
- Start date
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Could you have an air leak, which means outside air is getting in somewhere allowing the engine to rev? It could be a blown out seal or a crack in the intake boot. Only other thing I thought of was if you were in there twisting the screws, could you have raised the idle speed up that far? How about the high speed start lever, were you working around it?
Usually there are 2 fuel jets, L & H along with an external idle speed screw that holds the butterfly open. The high speed start lever holds the intake open for a quick start. If that start lever is out of whack that would cause the engine to rev. Usually when you blip the throttle that kicks the start lever down to the idle screw step.
I would set the fuel jets at 1.5 out from lightly seated and adjust from there. The idle speed screw is just a mechanical stop screw which holds the carb butterfly open. I would set that one at 1 turn in from when it first touches the external stop. Check the start lever by placing it in the start position without starting the engine, and blip the throttle to see if the system closes. That lever could have a small stick or some such stuck in it keeping it from working. Good luck with it and let us know what you find.
Usually there are 2 fuel jets, L & H along with an external idle speed screw that holds the butterfly open. The high speed start lever holds the intake open for a quick start. If that start lever is out of whack that would cause the engine to rev. Usually when you blip the throttle that kicks the start lever down to the idle screw step.
I would set the fuel jets at 1.5 out from lightly seated and adjust from there. The idle speed screw is just a mechanical stop screw which holds the carb butterfly open. I would set that one at 1 turn in from when it first touches the external stop. Check the start lever by placing it in the start position without starting the engine, and blip the throttle to see if the system closes. That lever could have a small stick or some such stuck in it keeping it from working. Good luck with it and let us know what you find.
Thanks, I’ll check into those things. I’ll let you know.
I got the saw to finally idle but I can’t feed it any gas without it instantly bogging down. I ran out of time to mess with it anymore today. I’ll pick it up tomorrow.
Vacuum and pressure test first. The carburetor cannot adjust to air entering the motor past the carburetor. After a handle compression test, fuel analysis, spark and piston condition check, it is the next thing on the list.
However, IF this is a two throttle shutter carburetor, make sure both are closed at idle. Seeing alot of this lately.
However, IF this is a two throttle shutter carburetor, make sure both are closed at idle. Seeing alot of this lately.
My own MS362 Strato charged started acting up and could not be adjusted to run properly, I did suspect the linkages between the two separate intake might have been out of sync or sticking but after a lot of close examination it appeared everything was operating properly. My contact at Stihl recommended changing the carb to an upgraded version/newer one so after a spell of not being able to get it working proper I did bite the bullet and order in a new carb, pricey yes but that fixed it right off the bat and still running fine 4 years after.
Likely a leaking circuit plug. They seem to work loose at random on chainsaws in general. It was common on the 361 carbs with the long oval circuit plugs.
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