Stihl 025

kyriverguy

Forum Newbie
Joined
Sep 28, 2014
Threads
2
Messages
2
only starts when using starting fluid , Replaced: air filter ,vent filter ,carburetor , spark plug ,fresh gas ,spark arrestor is clean. Any suggestions ?
 

Hammermechanicman

Lawn Addict
Joined
Jan 10, 2020
Threads
52
Messages
3,510
Did you check fuel line and filter?
Did you check the impulse line? It goes from a nipple on the cylinder to the handle assy that connects to a hole in the face of the carb.
Obvious fuel delivery problem.
 

Tbone0106

Active Member
Joined
Jun 1, 2017
Threads
0
Messages
67
Got to agree with the Drama Llama. Assuming you have good compression and spark, it ain't gettin' fuel.
Genuine Stihl parts for a saw that old will be hard to find. Amazon will sell you a set of stuff -- aftermarket fuel line, filter, and impulse line -- for like six bucks. Even a tiny crack in either of those lines will keep the saw from running.
One other thing to look at is the intake boot. Again, a little crack is all it takes, and those cracks can be hard to see.
 

StarTech

Lawn Royalty
Top Poster Of Month
Joined
Feb 19, 2020
Threads
76
Messages
10,219
The 025 is the old version of current MS250 saw.
 

bertsmobile1

Lawn Royalty
Joined
Nov 29, 2014
Threads
64
Messages
24,702
When did this start to happen ?
How was the saw running before it happened ?
Impossible to start cold but runs & starts fine hot is a classic symptom of leaking crankcase seals
Your saw will need to have both primary & secondary compression tested .
If the crankcase can not suck hard enough no fuel will enter .
Having said that where did you get the parts from ?
Are they branded parts or was it a "complete service kit" with unbranded parts ?
 

Hammermechanicman

Lawn Addict
Joined
Jan 10, 2020
Threads
52
Messages
3,510
If all the rubber on the 025 is original it really is time to replace them. Fuel, oil and impulse hoses. Fuel and oil filters. The crank seals and intake boot and the clutch drum bearing for good measure. Some stuff is available OEM still or aftermarket from HL Supply. Crank seals are fun to change. I just did an 028 a couple weeks ago.

Since you say it runs on starting fluid it has at least enough primary and secondary compression to run the saw.

Remove the carb and see if you can easily suck fuel out of the fuel line. If you can then install carb and pull the rope a dozen times then remove carb and remove the fuel pump side of the carb ( one screw) and see if there is fuel in that part of the carb. If not your impulse is not working. The small hole in the rubber intake boot the carb bolts up to is the impulse.
 

Tiger Small Engine

Well-Known Member
Joined
Dec 7, 2022
Threads
1
Messages
678
If all the rubber on the 025 is original it really is time to replace them. Fuel, oil and impulse hoses. Fuel and oil filters. The crank seals and intake boot and the clutch drum bearing for good measure. Some stuff is available OEM still or aftermarket from HL Supply. Crank seals are fun to change. I just did an 028 a couple weeks ago.

Since you say it runs on starting fluid it has at least enough primary and secondary compression to run the saw.

Remove the carb and see if you can easily suck fuel out of the fuel line. If you can then install carb and pull the rope a dozen times then remove carb and remove the fuel pump side of the carb ( one screw) and see if there is fuel in that part of the carb. If not your impulse is not working. The small hole in the rubber intake boot the carb bolts up to is the impulse.
Need to perform leak down test both vacuum and pressure with Mighty Vac tester. Need to pull muffler and check condition of piston, rings, and cylinder. A saw of that age needs these tests performed before going any further.
Merry Christmas!
 

Hammermechanicman

Lawn Addict
Joined
Jan 10, 2020
Threads
52
Messages
3,510
Need to perform leak down test both vacuum and pressure with Mighty Vac tester. Need to pull muffler and check condition of piston, rings, and cylinder. A saw of that age needs these tests performed before going any further.
Merry Christmas!
Kinda assumes he has the tools and know how to do that.
 

StarTech

Lawn Royalty
Top Poster Of Month
Joined
Feb 19, 2020
Threads
76
Messages
10,219
Kinda assumes he has the tools and know how to do that.
That's one of the problems here with users. Most don't have the knowledge yet alone the proper tools. Even with all the tools I have I am constantly having to add specialized tools.

Just because you know 4 cycle engines doesn't mean you know 2 cycle engines. They are a completely different beast. It took me nearly two years of constantly working on them to get anywhere good at repairing them. And it is a lot harder learning 2 cycles after you learn 4 cycles. It like flying aircraft. It is harder to learn rotary wing after learning fix wing.
 

Hammermechanicman

Lawn Addict
Joined
Jan 10, 2020
Threads
52
Messages
3,510
Yup 2 strokes are an animal all their own plus you have different types of 2 strokes. Piston port, reed valve, rotary valve, hybrid. Throw in all the older chainsaws that do things their way and a typical DIY guy is just lost in the weeds. And like star says you need a lot of special tools for 2 strokes, especially saws.
 
Top