Stihl 064 Tank Vent Problems?

[Dave P 71801]

I have a Sthil 064 that is filling the crankcase with fuel if it sits overnight. I know it’s coming through the impulse line because I unhooked from nipple on the case and connection a longer hose to it and put the end in a coffee can the next day there was fuel in the coffee can but none in the cases. I have pressure tested the carb and it will hold 6psi for over an hour. So I was thinking maybe the pressure in the tank was getting much higher causing the fuel to push through the carb. I live in southern Arkansas and I have seen gas cans, and even gas tanks in cars pop from pressure if the aren’t vented properly. So to test the tank vent I pulled vac through the fuel line and it equalizes in a few seconds but when I put 5 psi of pressure in the fuel line it holds constant so I thought i found the problem then I read the 064/066 manual and it seems to say that the tank vent equalizes both pressure and vacuum in the tank which makes sense but then a tech bulletin I read about an update to the tank vent seems to say the vent only allows air in the tank to equalize if there is vacuum but does nothing if pressure builds. So now I am confused I could really use some help. Here are some pictures of the vent maybe it’s just a mismatch of parts because I know the 1122 series is kinda known for changing. Any suggestions would be greatly appreciated

 

[L34]

The orange mushroom only let's air in not out.

 

[Dave P 71801]

The orange mushroom only let's air in not out.

Ok so is that wrong for my 064?

 

[Dave P 71801]

I’ve done some more reading and it seems like the vent is supposed to only allow air into the tank as fuel is used so if that is true how does pressure escape the tank? I pressure tested my carb again and took it up to 8 psi and it held perfectly fine I was scared to take it any higher and the manual only calls for 5.6 psi so is the tank pressure getting substantially higher to push fuel through the impulse line into the cases or is there something else wrong with the carb? If it is because the pressure is getting that high how is it supposed to escape and not push fuel into the cases? I’m totally confused