Stihl 026 Chainsaw Fuel Problems

[Rayrla]

My Stihl 026 has a fuel supply problem. When I pour some fuel directly into the carb, it runs for a few seconds and dies. I have removed the carb, the fuel line, and filter. I plan on purchasing a rebuild kit for the carb and new fuel line and filter. There is another line from the carb that appears to be going to the crankcase. I would like to replace this line as well, but cannot see how to access this line. Any suggestions would be appreciated. I purchased this saw back in 1995, and it has had zero problems until now. Thanks.

 

[xyz123]

That would be the impulse line.

 

[xyz123]

This video will show you impulse.

 

[RobertN]

I have not see a good description of the impulse line and how the whole system works.

 

[Rayrla]

I have not see a good description of the impulse line and how the whole system works.

From what I have read the impulse line supplies vacuum to enable fuel to flow to the carb from the tank. The engine heat causes the impulse line to degrade and fail over time. Even from the video above, I cannot see how to get the new line installed. It doesn't appear that removing the pull starter mechanism will open up enough space.

 

[yomax4]

Looking at mine, It looks like you just gently pull it out of the crank case and insert the new one in? Same with the fuel line?.

 

[xyz123]

There is a nipple on the crankcase it slides over. On the back of the carb mount area impulse line passes through plastic and attaches to carb on the bottom of carb on impulse nipple.

 

[LD1]

The impulse hose is what makes the diaphragm in the carb work to "pump" fuel.

As the piston travels up and down in the cylinder, this creates pressure and vacuum waves inside the crankcase. These "impulses" are transferred through the hose, and actuate the diaphragm in the carb to pump fuel.

 

[Rayrla]

Thanks to all who replied. When I get a few minutes over the next few days will give replacing the impulse line a try. Seems pretty tight where impulse line fits over crankcase nipple.

 

[xyz123]

2 words for this. Long forceps.

I have straight and curved set.

 

[Rayrla]

2 words for this. Long forceps.

I have straight and curved set.

Plus flashlight and lots of patience. Only could find straight forceps. Will pickup a curved set next time I visit Harbor Freight. Also helps to remove plastic plug and screw behind it on chain side of saw. Gives one a tiny bit more room to see the impulse hose. Saw is now running. Rebuilt carb, changed fuel line, tank filter and impulse hose. Final observations, carb filter was plugged, and for a 18 year old saw impulse hose was in good condition, somewhat soft with no breaks and fuel line also was in decent shape. Thanks for your help.

 

[yomax4]

This video will show you impulse.

Awesome. I watch the impulse Vid..Then I get a million others. Very cool stuff..

 

[xyz123]

I have a 440 all tore down if someone needs to see a impulse line in tank and where it goes through and crankcase separated to show line impulse nipple there too.
Let me know before I button it back up in a few days (waiting on parts) and I grab some pics.

 

[xyz123]

I have a 440 all tore down if someone needs to see a impulse line in tank and where it goes through and crankcase separated to show line impulse nipple there too.
Let me know before I button it back up in a few days (waiting on parts) and I grab some pics.

Too late now. Together and running again.