no idea, are you sure that is not the vent line? I just got a Stihl AV 012 going.. after hours on it.
turned out somehow to be the fuel line, the line in it was not transparent and I got suspicious when I blew air into it and then fuel spurted out from around the hole. so I decided to replace it with one that transparent, so I could see what was happening (it would cough start with some petrol medicine thrown down the carby manually).
I used the same orange transparent line 6mm as brushcutters use but first I drilled a hole out of where the line was coming out of.
drilled a hole and put a rubber gromet in (a bit dodgy as the depth of the hole is greater than the inner part of the gromet.
then I could see the fuel progress down the line.
there were no gromets there before (it might have been messed with), just a hole.
also had to modify the replacement carby and take out the choke lever, just put a couple of screws into the holes.
if I have issues with my gromet I might put a large grub screw in, and bore a hole with a smaller inner diameter in the middle to take a gromet.
just a guess but maybe someone thought to put a grub screw in the line to limit the fuel . I had this one catch fire twice, which I think was incorrect original carby kit I put in. but at least I knew the petrol was good, lol.
Last edited by petergrass; 17/04/23 12:48 PM.