Stihl 025 vent line fuel leak

[HarleyT]

Likely the carb still has a clogged up passage somewhere, and the diaphrams are likely stiff after 20 years. The Stihl dealer sells a brand new carb for under $30, 1123 120 0605

 

[pioneerguy600]

Yeah, I was just wondering if the vent line needed pushed on the nipple further. Either way, he could just push them in a bit more with a small screwdriver, as their placement is not critical. I am curious where this fuel is leaking from, as that would probably tell us something.
His running problem isn't the vent though, well that could be easily tested. Just take it off, and start it.

Come on Harley, yer getting slack, tell this guy what he needs to do with this 20 year old carb.

 

[Okie]

If you see gas bubbling up the vent line the vent line is doing it's thing.

Agree with Harley replace the carb. A OEM stihl carb kit cost almost same as new OEM Stihl carb and a kit may not fix the old carb plus your time goofing around with the old carb.

Also if you are ever moving them grub screws in the new vent hose PUSH THEM with the screwdriver or small punch instead of turning them.
If you turn them inside a soft vent hose they will seal instead of vent. Try it with a vacuum pump and you will see such.

And some vent hose (even tygon) is too soft to use with grub screws as a vent.

 

[HarleyT]

Well, if he buys a decent carb kit, he is almost halfway towards a new carb. This way, he could pop on the carb and go cut wood.

 

[HarleyT]

But before spending much of anything, he should pop off the muffler and look at his piston.

 

[HarleyT]

And of course, check and make sure that the impulse line is still connected.........

 

[PogoInTheWoods]

...and still replace the fuel line and filter (providing the piston looks good).

 

[ericm979]

I'm assuming the OP's observations are correct and fuel is bubbling out the tank vent. How would piston/cylinder damage or a cracked fuel line cause that?
From the description of the symptoms, I think that there's a problem inside the carb. There could be a hole in the pump diaphram or the flap valve that keeps fuel from being pumped back into the tank is not sealing. Or both. It's easy to damage the diaphram or valves when disassembling the carb as they are small and delicate. Of course they can also go bad without the carb being disassembled.

 

[HarleyT]

I suggested looking at the piston, mainly before spending a bunch of money.

I think that the amount of fuel coming out of that vent is a whole lot less than it was when the vent was missing......

 

[ericm979]

Yea it'll dribble fuel pretty well when the vent is missing, as I discovered last year. Saw was only 19 years old, damn German junk. I made one from a piece of fuel hose and a screw so I could use the saw until I got a new vent but it wasn't as good as the real Stihl one.

If my diagnosis is correct then a careful rebuild of the carb with new diaphram should fix it. Or as was suggested earlier, a new carb if they're not that much more expensive than a rebuild kit.

 

[HarleyT]

I think one could get a china one for $1.97, these days.

A new walbro from Stihl is under $30

 

[Okie]

Agree knowing it's a 20 year old saw, look at piston cylinder to make sure not throwing good money and time into bad or a dying horse.
Suspect carb is back feeding slight pressure to the gas tank and you say engine don't run good. If piston/cylinder ok, install new carb, fuel line, pulse hose so as to shoot for another 20 years of use. Normally anything that is 20 years old on a chainsaw and it's touched bothered or worried little bit it will crumble, not seal or crack for example the fuel line, pulse line and the vent hose. Keep your fingers crossed on the life of the intake boot.

I've got a reliable 40 year old 028 that I re-carbed at 20 years old with new fuel lines, etc and it's still going today.

Really don't like to admit this but: I've used them ebay $10 China carbs just to get a short run test idea if a OEM expensive carb might fix a saw's problem, but I do not leave the China clone carbs on for permanent use on a good saw. I then go OEM if I get a good test run. (and I've seen some of the cheapo China clone carbs and kits bad straight out of the package)

Put China stuff on it and it won't last very long or be reliable.

 

[Gypo Logger]

The insert on the top looks like it is farther in the fuel line, and might allow the fuel line to go down farther on the nipple.
Which is why I asked where the fuel was leaking from.

I am guessing that you have a severely cracked fuel line. Try bending the line with your fingers and looking.
Take a pic.

John, the proper terminology for the insert is grub screw. Stop spreading misinformation !

 

[PogoInTheWoods]

Technically, "slotted grub screw".

 

[HarleyT]

Trudeau has a problem with "insert" too? I am probably in trouble for the word "nipple" as well!

 

[HarleyT]

"Slotted" doesn't sound very inclusive.....


Kind of hateful........

 

[PogoInTheWoods]

...... and divisive.

 

[PogoInTheWoods]

Guess it sorta depends on if ya push it in or screw it in.

 

[Gypo Logger]

Ya but where did the nipple like slotted grub screw take a leak?

 

[HarleyT]

Guess it sorta depends on if ya push it in or screw it in.

Gotta mix it up to keep one's marriage alive.......