Where does this hose connect?

davidblaine

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I took the carb off my Stihl FS44 string trimmer and there is a hose coming off the gas tank, but where it runs to, I can't tell. When I took the screws out and removed the housing it was already lose, so I didn't remove it and am not sure where it goes. There are two other lines from the tank, a very short one to the primer bulb, and the main, filtered line to the carb. This must be either a vent or a return? I am attaching a diagram. The hose is number 12 and the connector is number 21. Can anyone advise where to route that? I don't see any obvious place on the carb.

stihl2.gif
 

Mower King

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12 is the vent tube - 21 is the vent, it does not connect anywhere...they are usually run up vertical from the tank out of the way......it vents the tank.
 
Last edited:

upupandaway

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12 is the vent tube - 21 is the vent, it does not connect anywhere...they are usually run up vertical from the tank out of the way......it vents the tank.
my "vent" leaked(thus no pressure) so i removed it and plugged it with a golf tee.
 

PTmowerMech

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I took the carb off my Stihl FS44 string trimmer and there is a hose coming off the gas tank, but where it runs to, I can't tell. When I took the screws out and removed the housing it was already lose, so I didn't remove it and am not sure where it goes. There are two other lines from the tank, a very short one to the primer bulb, and the main, filtered line to the carb. This must be either a vent or a return? I am attaching a diagram. The hose is number 12 and the connector is number 21. Can anyone advise where to route that? I don't see any obvious place on the carb.

View attachment 53087

Fuel filter to carb body. From the other carb outlet back to primer. Other primer nipple back to tank. The other, as @mower king stated, is a single line with a vent.

Primers suck fuel from the tank, through the carb then back to tank. You may already know that. But I remember when I first started working on these, thinking that the primer pushed fuel through the carb.
 

davidblaine

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my "vent" leaked(thus no pressure) so i removed it and plugged it with a golf tee.

Thank you, that was my hunch since I know that gas won't come out of an unvented container unless it's somehow pressurized. Also kind of explains why I heard something light moving inside when I took the engine off and was taking the cover off, like something was already loose.
 
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