Chainsaw won't idle

[Captain Caveman]

On 22/09/2020 at 23:05, Zapp said:

Maybe invest in some Aspen, if it wont run on that you can be more assured the mix is/isn't the problem 

Used Aspen in my saws for years. Expensive but seem to save on repairs to the block. Seems to work best in the newer saws with microchips.

[walshie]

Got it running again. Just ordered a little tacho so I can fine tune it so it's not running lean.

[lord_seagrave]

Just another thumbs up for Aspen fuel. My little side hustle very seldom strays into serious tree work, so my saw can go for months without being used.

starts and runs like a charm each time.

LS

[figgy]

Walshie you don't need a tacho. Run it flat out but running rich adjust the screw so it leans out with no coughing but for not long a second or two, then turn the screw untill starts fourstroking/running rich it will run then cough run and cough at full throttle,then when under load it will be perfect air to fuel ratio and run without the coughing stutter.

Edited September 29, 2020 by figgy

[walshie]

22 minutes ago, figgy said:

Walshie you don't need a tacho. Run it flat out but running rich adjust the screw so it leans out with no coughing but for not long a second or two, then turn the screw untill starts fourstroking/running rich it will run then cough run and cough at full throttle,then when under load it will be perfect air to fuel ratio and run without the coughing stutter.

👍 Thanks.

[hafod]

On 22/09/2020 at 19:57, walshie said:

I have small Stihl MS171 that I use for limbing and a few bits and pieces. It was starting to play up - not idling, bogging down when I tried to rev it etc. I bought a few parts that needed changing anyway and gave it a bit of a service.

I read about cleaning out the spark arrester, but it doesn't seem to have one. (The book said they don't all have them), so I gave the whole thing a good clean, new sprocket and chain, new air filter, fuel filter and plug.

I started it and it fired right up. It revs great but then it wouldn't idle for more than a few seconds. More reading and it suggested setting the carb settings back to stock settings. I've done that and it starts easily enough, it revs easily enough, but it won't idle at all now. 

Any ideas?

How old is the saw Sounds like it could be that the fuel pipe is perished its sucking air through the pipe into the carb sounds like the problem 

pull the pipe out of the tank with a pliers its an all in one self sealing pipe unit

Thread the new one through the tank pull through untill it reaseals its self

reattach to the carb push on a new tank fuel filter that might solve your problem 

[mellors]

Just ordered these for my old one it due a strip service. 

[bornfree]

Just had the same problem on a partner disc cutter. It was the metering needle in the carb not sealing. Easy to check if you have the equipment, remove fuel pipe connect a pressure gauge and pump to the fuel inlet on the carb, pressurise it to 7-10 psi and it shouldn't drop.