Stihl MS170 Hard to Start

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jays35

jays35

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I have a Stihl MS170 that is very hard to start when it hasn’t been running. It takes about 15-20 pulls on full choke to get it to hit. Once it hits, it will start, idle, and run fine. It will restart since it is warm and run fine. I have also tried to start with no choke and it will not run. Gas is new and it works fine in other saws.
Thanks in advance for any help!!

Dave
 
djetelina

djetelina

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My 1st Stihl was a MS170 which I bought new from the dealer ~5 years ago. Has been difficult to start since new, at least 4 or 5 pulls when cold. Carb on mine is not adjustable. Have pretty much learned to live with it. Start procedure is to pull on rope w/ full choke till engine hits. Then move to 1/2 choke to get it running.
 

J D

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The choke not engaging the throttle lock will cause this, as will a stiff pump diaphragm in the carb, as will a pin hole or poor seal on the fuel line or a blocked fuel filter. A weak or blocked impulse could cause similar issues too but that's far less likely
 
DanAyo

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I have a Stihl MS170 that is very hard to start when it hasn’t been running. It takes about 15-20 pulls on full choke to get it to hit. Once it hits, it will start, idle, and run fine. It will restart since it is warm and run fine. I have also tried to start with no choke and it will not run. Gas is new and it works fine in other saws.
Thanks in advance for any help!!

Dave
Try this.
  1. Remove the air filter cover. Get someone to place their thumb over the carb throat while you pull start the engine. If it starts quickly, your choke may be the issue.
  2. Second, try putting a small amount of fuel in the carb throat and then pull start. If it runs, a carb rebuild might work.
 
thenne1713

thenne1713

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My 1st Stihl was a MS170 which I bought new from the dealer ~5 years ago. Has been difficult to start since new, at least 4 or 5 pulls when cold. Carb on mine is not adjustable. Have pretty much learned to live with it. Start procedure is to pull on rope w/ full choke till engine hits. Then move to 1/2 choke to get it running.
Fuel must be able to free-flow when needed; lines too long= bent/crimp, flow but not free-flow; trim to fit, sometimes trimming 1/8" cures all.
 
SAWTECH1

SAWTECH1

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I would check the in pulse line for signs of cracking, also install new plug. Some of the 170/ 180 have issues with carbs that come from the factory, you may also perform press/vac test on the carb, may even check the vent cap in the fuel tank( duck bill).
 
TheJollyLogger

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Reading back on the original post, and thinking back on my muscle memory...
Stihls are notoriously easy to flood, especially when cold starting. I would never pull more than 5 times on full choke, whether I got a "pop" or not. I would always kick it up to 1/2 choke after 5 pulls, and it would usually cough and fire from there. 15 or 20 pulls on full choke is sure to flood it.

Of course the best way, and certainly not OSHA approved way to clear out a flooded Stihl is to point it away from yourself, hold the throttle full in and crank away until it clears itself out.
 

J D

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Reading back on the original post, and thinking back on my muscle memory...
Stihls are notoriously easy to flood, especially when cold starting. I would never pull more than 5 times on full choke, whether I got a "pop" or not. I would always kick it up to 1/2 choke after 5 pulls, and it would usually cough and fire from there. 15 or 20 pulls on full choke is sure to flood it.

Of course the best way, and certainly not OSHA approved way to clear out a flooded Stihl is to point it away from yourself, hold the throttle full in and crank away until it clears itself out.
Agreed, but the OP said that after 20 odd pulls it eventually starts & then runs fine... If it's flooding that wouldn't be the case.
I would suspect something is impeding the carbs ability to initially draw fuel up
 
Kensterfly

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My 170 died a couple weeks ago and wouldn’t restart. Period. I found the spark arrestor pretty clogged. I just removed it. Still no start. The air filter was clean. I pulled the plug, it was dry and looked clean. Then I noticed a tiny bit of debris in the plug gap. I gave the plug a good brushing and it fired right up. It has run flawlessly since as I’ve given it a good workout nearly every day cutting trails in our woods.
You never know what tiny little thing will prevent a start up.
 
Steelthumb

Steelthumb

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I have a Stihl MS170 that is very hard to start when it hasn’t been running. It takes about 15-20 pulls on full choke to get it to hit. Once it hits, it will start, idle, and run fine. It will restart since it is warm and run fine. I have also tried to start with no choke and it will not run. Gas is new and it works fine in other saws.
Thanks in advance for any help!!

Dave
My MS170 is also finicky. I need fresh high octane fuel to get it going. Since starter fluid can't be used without risk of engine damage, I use some Stihl Motomix fuel to start it and warm it when I'm in a pinch.
 
Kensterfly

Kensterfly

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My MS170 is also finicky. I need fresh high octane fuel to get it going. Since starter fluid can't be used without risk of engine damage, I use some Stihl Motomix fuel to start it and warm it when I'm in a pinch.
I had the same problem recently. Cleaned the spark arrestor though it wasn’t bad. Air filter was like new. Pulled the spark plug and spotted a tiny bit of debris in the gap. Gave it a good brushing and it fired right up. Starts easily now.
 
sonny580

sonny580

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sounds like my ms 250! lol! I finally had to buy a chimna knockoff carb that has load needles and that got it running decent but if it sits for 3 weeks or more,----take air filter off,--dump a bit of gas in and usually will start the first pull after that. --- then shut it off and put air filter back on and go cut wood.
 

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