New to primer bulbs.....

[andrethegiant70]

Hello again, my brothers (and maybe sisters?). I like old school stuff so I haven't had anything with a primer bulb to date. I just picked up a used BG85 blower (yes, good compression) that seems in good shape. Pops with mix down the carb, so I think it's non running status can be remedied with a little fuel system work. Here's the deal.... when pressed, the primer bulb does not fill with fuel... I CAN hear it doing something. After a few pumps, if you unscrew the fuel cap, it goes "foof!"... the bulb is creating pressure in the tank without moving any fuel. I can tell it's positive pressure because when I pop a fuel line off, I get a good shot of fuel. Where it's getting air is a mystery to me, but it does not seem like it's pulling it from the tank, or it would be a zero-sum game and, thus, no pressure. It appears to me that the fuel lines are hooked up in the correct sequence. In order to rule out a fuel line crack near the top of the fuel line (inside the tank), I tipped the unit over on its side to cover the whole grommet with fuel. Same result.

So... still not a primer bulb fan. But I like this unit and could use some advice on getting the carb straightened out. Much obliged for any help given....

 

[HarleyT]

It is not really a primer bulb, but a purge. It pulls fuel through the carb and sends it back to the tank, "purging" the carb of air. Makes starting a little easier.
Sounds like you just need to disassemble the carb and clean it.

 

[HarleyT]

Or just get a new carb from your Stihl dealer for $25
#4229 120 0604

 

[HarleyT]

Carb kit from Stihl costs $17

 

[andrethegiant70]

So maybe a blocked passage? If a newie is $25, that seems like good insurance.

Sure appreciate it, gents.