I'm not real familiar with fuel venting on saws. The only vents i've been aware of are the vented caps on those 600-series Macs. Awhile ago I found the far end of the fuel vent hose on my Partner P100/Mac PM1000 had rotted off, it's seen a lot of sitting. I located an IPL for the P100 and one for the PM1000. Called over to Wallenberg's to see if they could help me out. I told them I wanted the whole fuel vent hose assembly from the tank out. Can't remember if I gave them part numbers or not. On shipment, I received a nipple piece, a hose, and a round strainer screen. I called back and asked in what format the parts went together onto the tank. He thought the strainer stopped the fuel from coming out. That made sense to me as the 600-series Macs have a strainer in the cap. Unfortunately, he couldn't tell me 100% for sure, and his mechanic wasn't in, and whenever I call now for some reason his mechanic isn't in. So I went to install stuff today. I inserted the strainer screen into the one end of the hose, and I noticed that the nipple piece he sent was the same piece as was stuck into the grommet in the tank, so I just made sure mine was open and reused it. Figuring this was correct, I installed it and tested it for seaping. Looked good when I put the hose in the firewall holder. I tipped the saw on the recoil side to pull out the spark arrestor, and after about 5 minutes started smelling fuel. Sure enough, my stainless top on my toolbox was soaked in fuel. It was wet by the strainer end, as well as the grommet end, but that may just be from feeding from one of the ends.
After searching awhile, there is a lot mentioned about a one-way valve in those types of venting systems (hose vents). I did notice tonight on the IPL that there is another piece at the far end of the hose after the strainer. Does that work in series with the strainer, or is the strainer a stand-alone piece? What benefit would the strainer be if there was a valve after it? Really just would like to hear some insight on how this works.
I'm really no expert at these saws, or any saws, but more of an enthusiast. So I appreciate the friendly advice if anyone has any. (I will keep searching, for those that might mention to search more.)