Stihl 025 gas leak

[JackJ]

I've got a Stihl 025 that's about 20 years old. Just noticed that with about 1/4 tank of fuel left, it's leaking gas somewhere, even after sitting upright and untouched for a couple of days. I don't think it can be the filler cap, the vent line, the fuel line, or the carb, since all of those are above the fuel level when the saw is sitting upright. It appears to be on the flywheel side.

Any ideas where this could be coming from? Could a crankcase seal leak fuel days after the saw has been run? Do these tanks ever develop small cracks? Not sure where the impulse line is tucked away, but it's never been changed, so could that be it?

It's probably only an ounce or so a day, but I keep noticing a little more each time I check by setting it on a fresh paper towel.

Thanks for any ideas,
Jack

 

[merc_man]

Presureize the tank and check with soapy water for leake.

It could be the fuel line. The tank will build presure by it self from the gas

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[Kenskip1]

I would look at the fuel line.Most likely a crack. It may be the original line.It is an easy fix.

 

[JackJ]

Forgot to mention that I just changed the fuel line/filter (for the first time in 20 years) shortly before noticing the leak. Bought the new fuel line at the local Stihl dealer, so I hope it's OEM and don't think it could be cracked. I guess it's possible I didn't get it seated correctly where it enters the tank, but didn't think it could leak there when the saw is upright and the tank just 1/4 full.

 

[merc_man]

My ms 250 was leaking where line went on carb. I had to put a small zip tie on it. Mabe check that.

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[JackJ]

Presureize the tank and check with soapy water for leake.

Any good way to pressurize without a specialized tool? I'm obviously new at this.

 

[merc_man]

If ya got a compresser put about 5-10 psi through the fuel line into tank and spray soapy water till ya see bubbles. Or so it the old fasion way and blow through hose with mouth.

Empy gas out first.

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[JackJ]

If ya got a compresser put about 5-10 psi through the fuel line into tank and spray soapy water till ya see bubbles. Or so it the old fasion way and blow through hose with mouth.

Empy gas out first.

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Thanks! I should be able to do that.

 

[merc_man]

Ok. Let us know we can all walk ya through it.

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[Chainsaw Jim]

Pressure can build in the tank and force the fuel up through the fuel line and out the carb, even when the tank is empty if there is still some fuel in the line. This usually happens when the metering lever is too high or stuck open.
Any leak in the fuel line outside the tank will do this....as mentioned above by another member with the loose connection that needed clamped.