Chainsaw won't idle after wot

[jdvsn83]

Hey guys, I'm having problems with my Echo CS-350TES.

It idles ok after cold and warm start. Goes from idle to WOT with no problems, but won't idle after cutting. I have to release the throotle trigger too gently to keep it running.

It gets worse with the conventional carburetor low speed tunning (L needle between load up condition and fuel starving). Seems to get better adjusting at higher idle speeds and opening L needle a little...

Help needed!

Thank you!

 

[rd35]

First thing I would check is to make sure the carb nuts and jug bolts are all tight. Sounds like it's developing an air leak when it gets hot under load.

 

[jdvsn83]

First thing I would check is to make sure the carb nuts and jug bolts are all tight. Sounds like it's developing an air leak when it gets hot under load.

Thank you. The carb was ok

Now I'm dismounting the saw. It's a clamshell with bolts facing the gas tank, so I have to take the engine out...

 

[Chainsaw Jim]

How about a carb rebuild with a new kit?

 

[backhoelover]

sound like the nozzle check valve is not closing off when returning to idle

 

[jdvsn83]

How about a carb rebuild with a new kit?

Done with no improvements!!! Thanks!

 

[jdvsn83]

sound like the nozzle check valve is not closing off when returning to idle

Is that issue fixable?

 

[jdvsn83]

First thing I would check is to make sure the carb nuts and jug bolts are all tight. Sounds like it's developing an air leak when it gets hot under load.

Carb and jug bolts are ok.

 

[Chainsaw Jim]

Is your metering lever setting correct? That might be something to double check.
It might also be time to replace the crank seals.

 

[jdvsn83]

Is your metering lever setting correct? That might be something to double check.
It might also be time to replace the crank seals.

Metering lever is adjusted by workshop manual specs. Is it possible to have problems with crank seals in a barely used saw (max. 20 hours)?

 

[Chainsaw Jim]

Metering lever is adjusted by workshop manual specs. Is it possible to have problems with crank seals in a barely used saw (max. 20 hours)?

It's that new huh? What about that kick ass echo warranty everyone keeps bragging about? I would never work on my own saw if it was under warranty and I work on chainsaws for a living.

 

[jdvsn83]

It's that new huh? What about that kick ass echo warranty everyone keeps bragging about? I would never work on my own saw if it was under warranty and I work on chainsaws for a living.

Here in Argentina they come with only 6 month warranty. Stihl and Husqvarna too, I have a Stihl HS81R with problems since new and nobody fixed it under warranty. Had to pay parts and labour... I don't know how is it in the USA.

 

[Chainsaw Jim]

I think it is 4 years for echo in the states. Professional use Stihl and husky are about 3 weeks. Professional husky models sold to homeowners or ranchers come with 2 year warranty. all homeowner/ranch use Stihl and husky saws are 2 years.

 

[spudulike]

Sounds like you are either depleting the saw of available fuel during a long cut or it is running rich at the top end and is loading up to the point it dies on idle. If it is the first, check fuel line is OK, metering arm is at the correct height and worth pulling the H & L screws and trying a bit of carb cleaner. Also check the fuel tank breather with a pressure gauge and make sure it will let in air to replace fuel being used.

Make sure the fuel filter is good, make sure the fuel line isn't hung up keeping the filter out of the fuel. It sounds like you have tried different carb settings - what happens if the saw is left to idle for a few minutes and is then revved hard? Lots of smoke and the L screw is too rich! It is pretty easy to get the idle screw too far in to the point the L screw doesn't work as it should due to the throttle valve being too open.

 

[jdvsn83]

Sounds like you are either depleting the saw of available fuel during a long cut or it is running rich at the top end and is loading up to the point it dies on idle. If it is the first, check fuel line is OK, metering arm is at the correct height and worth pulling the H & L screws and trying a bit of carb cleaner. Also check the fuel tank breather with a pressure gauge and make sure it will let in air to replace fuel being used.

Make sure the fuel filter is good, make sure the fuel line isn't hung up keeping the filter out of the fuel. It sounds like you have tried different carb settings - what happens if the saw is left to idle for a few minutes and is then revved hard? Lots of smoke and the L screw is too rich! It is pretty easy to get the idle screw too far in to the point the L screw doesn't work as it should due to the throttle valve being too open.

Thank you very much spudulike.

First I apologize for my poor english.

Let's see:
- The saw cuts flawlessly and does the same at WOT with no load, tuned by ear and verified with a tachometer (13,000 - 13,200 RPM). It will 4 strokes slightly if I release the load in the cut, so I think the carb is getting enough fuel.
- Fuel line and impulse line checked twice.
- Metering arm is ok.
- Carb was cleaned 3 times, dissasembled.
- I tried with no fuel cap to test tank breather, is it ok?
- Filter is good and tried with a new one. The line isn't hung up.
- I gave it a run today, next to carb reassembly, and obtained different results: If I adjust the carb the way I learned it since I was 15 (L needle something between highest speed and load up condition, and smooth acceleration) it will run well and idle for 5 or 6 cuts, then it'll rev up when I release the trigger (like an air leak or lean idle condition), but It will return to idle if I press the throttle trigger a couple of times. The funny thing is that at WOT it won't race after lean idle condition... On the other side, it won't show any air leak symptoms when L is adjusted rich, but will smoke as you said, and stall after the first cut...

 

[spudulike]

Thank you very much spudulike.

First I apologize for my poor english.

Let's see:
- The saw cuts flawlessly and does the same at WOT with no load, tuned by ear and verified with a tachometer (13,000 - 13,200 RPM). It will 4 strokes slightly if I release the load in the cut, so I think the carb is getting enough fuel.
- Fuel line and impulse line checked twice.
- Metering arm is ok.
- Carb was cleaned 3 times, dissasembled.
- I tried with no fuel cap to test tank breather, is it ok?
- Filter is good and tried with a new one. The line isn't hung up.
- I gave it a run today, next to carb reassembly, and obtained different results: If I adjust the carb the way I learned it since I was 15 (L needle something between highest speed and load up condition, and smooth acceleration) it will run well and idle for 5 or 6 cuts, then it'll rev up when I release the trigger (like an air leak or lean idle condition), but It will return to idle if I press the throttle trigger a couple of times. The funny thing is that at WOT it won't race after lean idle condition... On the other side, it won't show any air leak symptoms when L is adjusted rich, but will smoke as you said, and stall after the first cut...

Try increasing the flywheel coil gap to 0.6-0.8mm. I have had two huskys set to factory spec and the idle was awful but doing this changes the timing slightly and it works.

It would appear that the gap was too small and was kidding the electronics that the engine was spinning faster than it was so it gave full advance at idle speeds killing the idle.

Try it, it may work for you!

 

[Chris-PA]

Maybe there is something mechanically inconsistent about the idle condition, such as the throttle plate not returning to the same position each time. Does the carb have an accelerator pump? If so it should be visible on the throttle plate face of the carb. This could be leaking or be another place that linkage could be binding or hanging up.

I have one quite modified saw that will sometime stall if a close the throttle quickly after a long cut, but it is not so extreme. I have not figured it out yet but I'm pretty sure it is a fuel mixture issue and not a mechanical linkage problem. But yours is a stock saw and I would not expect similar issues.

 

[jdvsn83]

Thank you very much for your help guys.

Today's update:

It worked perfect for about 10 minutes with the coil gap readjusted to 0.7 mm.

Two pulls to start, flawless cold idle.
10 minutes cutting with no stall after cuts, and great idle but...
It started to accelerate on idle like an air leak or low fuel first, and then to bog down with trigger pressure...

Is there something I'm missing?

Put a new tank breather trying to issolate the issue.

 

[jdvsn83]

Maybe there is something mechanically inconsistent about the idle condition, such as the throttle plate not returning to the same position each time. Does the carb have an accelerator pump? If so it should be visible on the throttle plate face of the carb. This could be leaking or be another place that linkage could be binding or hanging up.

I have one quite modified saw that will sometime stall if a close the throttle quickly after a long cut, but it is not so extreme. I have not figured it out yet but I'm pretty sure it is a fuel mixture issue and not a mechanical linkage problem. But yours is a stock saw and I would not expect similar issues.

No accelerator pump. Linkage seems fine, and it runs great when cold...

 

[jdvsn83]

I think I'll pressure and vacum test the engine, cause it isn't working as it should be...