Sucking sound on gas cap opening

[foundationapps]

Hi folks, this should be easier than I'm making it out to be. Huge sucking sound (not on the wallet) when I open the gas cap to add fuel. Only happens when the tank bag was mounted up, stop and refuel. Could this mean a vent line is kinked, 2 of them one for air intake to equalize pressure?

[dirtrider]

Afternoon foundationapps

 

Yes, either a kinked or mis-connected tank vent line OR the Evap Can & (on rear of bike) is plugged.

 

Usually it is a severely plugged Evap Can.

 

Even though illegal to do so a lot of riders remove the Evap Can then terminate the tank vent behind the R/H riders foot peg (if you do this be sure to cut the end of the vent hose at an angle so it doesn't suck water into the tank).

[szurszewski]

Fix it - one way or another - ASAP - it's possible for this to result in damage to the sending portion of your fuel gauge system (if it hasn't done so already).

DAMHIK

[foundationapps]

Excellent, I found two lines off the tank, one is short, the other is long. The short one is plugged with an allen bolt! Which line should be open? Should I leave them both open?

 

I removed that carbon unit when I first got the bike.

 

Thanks ski from Portland on that get it done note.

[dirtrider]

Evening foundationapps

 

One line is the water drain from the fuel filler cap ring & the other is the actual tank vent (both need to be open & run to behind the R/H foot peg)

 

Blow back through them with tank filler cap open to tell which is which. One will come out inside the tank the other will come out in the small hole in the filler cap ring.

[foundationapps]

Roger that, thank you sir.

[AndyS]

The fuel pump plate on the underside of the tank is where the 2 breathers transition into the tank. These can block and rust preventing the breathers/overflow from working.