vacuum valve

Can somebody tell me how this gets put back together. I’ve had it put two different ways, but gas is still not going through!? This routes from the petcock to the carburetors. I’ve looked it up as much as I could, how the fuel line goes & vacuum line & air vent line… my bike starts but I’ve had...

So I’m a first time bike owner. I found a ‘83 CB750 on marketplace, got it for $325. Reason being so low, the guy got a new bike(Harley) & he had originally lost the keys back in 2020. I got it in the beginning of March, so she sat for a good while. I got new keys made, did an oil change...