Originally Posted by johngil
Totally unrelated I'm sure, but I started getting the sucking sound when opening my fuel cap. Was a little worried, but didn't suffer any performance issues.
On further inspection I found the vent line to be pinched closed due to my shock body (after a bent shock bolt) pinched the line against the sub-frame.
Never hurts to check.
Mine's had the "sucking" sound since the first tank fill.