Old Stihl 025. Cranks but won't run.

[Peter 315]

Did you look at the diaphragm? Mine was bad once I change it the engine started right up..

 

[dieselcrawler]

I've got 2 of the 025s, I've worked the he!! outta them over the last 20 years. Had nearly no issues aside from needle bearing and drive sprocket on one of them.
But... I worked on several Stihl saws at my former job, and you're on the right track if you've pulled the muffler and cleaned the exhaust port, fresh gas, etc. I agree i may be in the fuel lines, they aren't terrible to change but be sure to get factory parts.

 

[yomax4]

20 year old saw with original fuel and impulse lines. I think you start here. Inexpensive fix.

 

[N80]

I've ordered a new fuel line. If that doesn't work I'll replace the impulse line as well (whatever that is). Not sure I want to tackle a carb rebuild.

 

[kenmac]

I've ordered a new fuel line. If that doesn't work I'll replace the impulse line as well (whatever that is). Not sure I want to tackle a carb rebuild.

I think you can buy those carbs on line .
I have taken those small carbs apart and installed new diaphragms.
I find it very difficult to do with these fat fingers. Most likely will just purchase a new carb next time

 

[dodge man]

The impulse line is just another line that looks like a fuel line. It connects to the cylinder. I just rebuilt a MS250, which is very similar but a newer model of your saw. They are amazing simple to work. I wouldn’t be afraid to tear into the carb at all. Sometimes just taking it apart and cleaning it is enough, but parts off Amazon are very cheap if it needs some. New a MS 250 goes for $350 to $400 so it’s worth fixing.

 

[dodge man]

I just looked up prices on Amazon, a carb kit is about $7.00. A new carb, which includes gaskets, new fuel and impulse line, new air cleaner, is about $16. I personally would trust the original carb more unless it’s physically broken.

 

[Deere Dude]

Small crack or pinhole in the fuel line can cause this kind of problem.

Just had my 026 fixed by installing a new fuel line and new elbow going into the carb. Leaked around fitting (30 YO) and elbow was cracked.

Starts before I ever pull the rope now. Just kidding, but very surprisingly from cold it started on first pull. I am tempted to go and try it but don't want to jinx it.

 

[N80]

Thanks guys. Replaced the fuel line yesterday. Now it won't even turn over at all. Acts like it is flooded. Spark plug very wet so I know fuel is getting there.

Odd that it went from turning over but not running to nothing at all.

I loosened the handle and body work screws to get at the top of the fuel tank. Wonder if I loosened something? How is the carb connected to the cylinder? Or maybe I damaged a spark wire or something.

Anyway, will probably tear down the whole saw today. Got a little time to piddle around.

 

[dodge man]

There is a short rubber boot, a couple of inches long roughly, that connects the carb to the cylinder. If the spark plug is wet, itç—´ probably getting at least some fuel. Do you have spark? Did you take the muffler off and take a peak at the piston and rings?

I rebuilt my 250 and they are pretty easy to work on if you have a few skills and tools. The pic is one broken down and cleaned. If you look at my pic in the far right, you can see the main body that is white with the ignition module attached. If you have no spark that would be easy to change out.