# Stihl BG55 Leaf Blower leaking gas out of exhaust



## G-Mann

I have a BG55 leaf blower that leaks gas out of the exhaust muffler while the thing just sits. (not running). The last time I used it, it had about 4 to 5 ounces of fuel in the tank. It leaked until the tank was dry! The first time I noticed this, it started and ran fine no problems. However I cannot figure out why the thing is sucking gas out of the tank because on this model the carburetor is mounted above the tank. What do I look for to correct this situation?


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## geogrubb

The fuel inlet needle is not sealing properly, you need to clean and rebuild the carb, as the engine runs it builds pressure in the fuel tank. If you will lossen the fuel cap when you shut off the blower so as to relieve the pressure then retighten it. This should get you by until you can rebuild the carb. Have a good one. Geo


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## Sawmill Mike

G-Mann said:


> I have a BG55 leaf blower that leaks gas out of the exhaust muffler while the thing just sits. (not running). The last time I used it, it had about 4 to 5 ounces of fuel in the tank. It leaked until the tank was dry! The first time I noticed this, it started and ran fine no problems. However I cannot figure out why the thing is sucking gas out of the tank because on this model the carburetor is mounted above the tank. What do I look for to correct this situation?


If blower looses gas into engine when storage or shut off here is the problem. You must replace the tank valve and carb needle and metering diaphragm.

A bg55 I series in general use a duckbill 2 way fuel vent. With age or dirt these fail and allow the tank to pressurize as fuel cap gas O ring to seal. As warm engine causes fuel to expand pressure pushes it past the needle which partially opens from diaphragm chamber pressure on needle lever. The tank pressure also stretches metering diaphragm as well. When operating probably tank pressure will vent at .05 bar which is less than1 psi.
Conversely if you engine dies out or starves for fuel while running and opening the fuel cap makes it better the tank vent has failed to vent on inlet and should've replaced as well. Unlike cheaper blowers that use foam or overflow lines stihl uses the valve that pops into fuel tank itself.


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