I have a 94 (off/on/res no prime) petcock. The bike recently started running poorly and then wouldn't start. I disconnected the fuel line from the petcock valve to the carb and cycled the valve between positions. I got no fuel and the line seemed dry inside. However, I'm not sure how the vac valve works (where it's vac source is,how it works) so I'm not sure if that's normal and I just need to apply suction to the valve somewhere.
Also, I thought the other 2 lines were feed lines but it appears the valve is actually partially in the tank so I'm not sure what the other 2 lines are.