Fuel pressure and gas cap vent leakage.

[Brushwacker]

My 032 I have brought back to life that I've been working on getting any bugs out of leaked gas out of its fuel cap vent when pointing it upward to trim limbs.I found another cap that has a red rubber disc shaped piece that covers the inside middle part of the cap.I could blow into this cap but not suck out. I tried this and fuel would leak out the carb soon after I started engine at idle and when I shut it off. I removed the fuel line from the carb while it was still leaking, and fuel came out the line with pressure. When I loosened the cap it stopped,when I would snug the cap it would begin running out the line again.I switched caps and it did not come out, so I switched back and the pressure came back enough to leak some more. So should a properly functioning cap leak through the vent when pointing the saw upward cutting on this saw?Should these caps all have the red rubber disc in the middle? I would appreciate any and all information anyone can give me concerning this issue. Thanks.

 

[Lakeside53]

All the 031 and 032 leak from the fuel cap.

There are a couple of different styles of caps, neither of which are available new from Stihl. You can buy the various parts for the vent system though. Yes, there is a rubber disk, but it just doesn't seal all that well at low pressure. Make sure the small grub screw is in the cap.

 

[Brushwacker]

Thanks. I thought that might be the case but was not sure. I do not remember any of my newer saws spitting any gas on me when reaching up with the bar.
Found another cap and took the middle out,cleaned it,drilled the center hole out a tad so the grub screw wouldn't be to snug. Mabe this one will work well and not leak as bad.