MANTIS TILLER

[flh69]

I bought a used Mantis Tiller and got it running with a little TLC. I used it this morning in my garden and it kept acting like it was running out of gas. This thing has an external breather connected to a hose from the tank. I removed the breather and it ran ok. I replaced it with an aftermarket one I had and it went back to acting like it was running out of gas. I opened the little breather and removed the duck bill. Put the breather without the duckbill back on and it ran ok. What is the purpose of the duck bill?

 

[Woodwackr]

I bought a used Mantis Tiller and got it running with a little TLC. I used it this morning in my garden and it kept acting like it was running out of gas. This thing has an external breather connected to a hose from the tank. I removed the breather and it ran ok. I replaced it with an aftermarket one I had and it went back to acting like it was running out of gas. I opened the little breather and removed the duck bill. Put the breather without the duckbill back on and it ran ok. What is the purpose of the duck bill?
View attachment 452326

Makes the vent one-way.
Reminds me…need to put the new carb on mine before garden time

If your mod works and doesn’t leak gas…problem solved

 

[EFSM]

Unless the valve is somehow not opening and allowing air to enter the tank, that is probably not the entire issue. It sounds like the carburetor is not pumping fuel properly.

 

[GMB74]

The duckbill is a one-way valve allowing air into the fuel tank as the fuel is consumed. It should not allow fuel or fuel vapors to leave the tank through the vent. The original one was probably old, had hardened rubber or dirty and was plugged. Check the replacement duckbill carefully to see if it was made properly and will open to allow air through. The replacement aftermarket valve likely is malformed and not working properly. Typical for aftermarket Chinese parts, they may or may not work right.
If the problem persists, something else is going on. Plugged fuel filter? Collapsing fuel line?