Stihl 025 major fuel leak

[Rich Purdum]

I live in Sierra Foothills outside of Auburn and we got whacked by heavy snow (for us) on 12/17. No grid power until 5:00 PM on 1/8 and still lots of snow and of course downed limbs and trees too. Pulled the 025 out, filled it up and was astonished by the MAJOR pool of fuel on the floor. The saw was on it's right side and empty when I started. There was LOTS of fuel on the floor.
The good news is my pro tree guy was able to get me to a point where it's almost normal. We have some trees which are beyond saving (fir and pine) and lots of chipping to be done..my guy Kevin will be back next week not to worry. A neighbor lost a century old live oak...snow load just pulled it out of the ground and next door a live oak lost about half. I think they had it removed. Sorry, this has drifted into "snow and trees"...it's the heaviest at our elevation in a long while and all the "weak sisters" came down. Without power we decided to seek a motel and the PG&E crews from out of the area had booked all the rooms!

So, as near as I can tell there are two "leak points" in an 025 tank...the feed to the carb and the vent. Is there someplace else I should look? As near as I can tell the main fuel line to the carb is fine. The vent seems to be "dribbling" a bit. Fuel seems to be coming from under the saw. Where to look?

 

[a. palmer jr.]

Other than the gas cap and the other two points you spoke of, the only thing left would be the seam on the fuel tank unless maybe the carburetor or fuel line is leaking.

 

[Woodslasher]

The vent should vent a little bit of fuel, but if you have a leak I'd check that and your fuel cap. I'm roughly 30-40 minutes away from you over by Placerville, if you wind up needing a hand I'd be happy to meet up somewhere and take a look at it.

 

[Rich Purdum]

Other than the gas cap and the other two points you spoke of, the only thing left would be the seam on the fuel tank unless maybe the carburetor or fuel line is leaking.

On the 025 the tank is integral to the "motor housing"...it is part of a complex molding and if it has failed the saw is dust. I will look "down stream" and see if I can spot the source. I can not recall the last time I used the saw, it was certainly pre-pandemic.

 

[Rich Purdum]

The vent should vent a little bit of fuel, but if you have a leak I'd check that and your fuel cap. I'm roughly 30-40 minutes away from you over by Placerville, if you wind up needing a hand I'd be happy to meet up somewhere and take a look at it.

Appreciate the offer for a "consult". After our "snowed in" two week ago the wife has been itching for an outing. Advice on the saw would for sure be worth a good lunch close to your place. I will give it one more shot on spotting the failure tomorrow and report back.

 

[Rich Purdum]

This afternoon I went back to square one and filled the tank. No leaks! There was a lot of "dribble" from the vent once I closed up the cap. I noticed that I need to really tighten down the cap to where it stops. The only thing I can figure is the tool sat with a dry tank for two years. Once it got "wet" for a while, things sealed back up...sort of like the wooden boat out of water. Don't forget this saw is probably 40 years old and my SIL never really took care of it. I'd like to address the vent leak as it seems excessive. Can I install one of the new style vents? Mine is the old "tube and screw" style. I figure I'll also replace the fuel and oil caps and the fuel filter (probably original). I would imagine the spark plug is original so should I replace that too while I'm at it?

 

[a. palmer jr.]

This afternoon I went back to square one and filled the tank. No leaks! There was a lot of "dribble" from the vent once I closed up the cap. I noticed that I need to really tighten down the cap to where it stops. The only thing I can figure is the tool sat with a dry tank for two years. Once it got "wet" for a while, things sealed back up...sort of like the wooden boat out of water. Don't forget this saw is probably 40 years old and my SIL never really took care of it. I'd like to address the vent leak as it seems excessive. Can I install one of the new style vents? Mine is the old "tube and screw" style. I figure I'll also replace the fuel and oil caps and the fuel filter (probably original). I would imagine the spark plug is original so should I replace that too while I'm at it?

I like to use the Echo style vent tube on those Stihl saws that have the tube and screw arrangement. They look like a fuel hose with a white mushroom on top of it and they work well. You can find them on ebay or at an Echo dealer but the dealer price is way higher.

 

[SteveSr]

... I noticed that I need to really tighten down the cap to where it stops

New cap gaskets are available from Stihl and should solve that issue

I'd like to address the vent leak as it seems excessive. Can I install one of the new style vents? Mine is the old "tube and screw" style.

Yes, you can hook the newer MS250 style of vent or one of the Echo vents to the tank with a piece of fuel hose. This should stop any vent leaks.

I figure I'll also replace the fuel and oil caps and the fuel filter (probably original).

Cap gaskets are cheap. I would also replace the fuel and impulse lines while you are at it for cheap insurance.

Due to age I would also look into putting an OEM kit into the carb. More cheap insurance.

I would imagine the spark plug is original so should I replace that too while I'm at it?

I don't usually as you'll never wear one out in a homeowner saw. As long as it is tuned correctly and used properly the plug should stay fairly clean.