[shadowmac83]

So, i pulled the gas tank off today and found a hose on the bottom of the tank by the petcock plugged with a screw. there is another that is not plugged and is attached at the other end to the top of the carbs. haynes manual calls it an air hose? kind of a generic name. should these have been connected or is it a coincidence that theyre next to one another?
my gas tank doesnt hold a vacuum if thats any help, and i am running rich and idling funny. i really hope this fixes it.

 

[Nehalem Dave]

I suspect you saying vacuum but you mean vent.

 

[shadowmac83]

possibly. hence the title "mystery". thanks for the input.

 

[SteveSchu]

That is the fuel tank VENT line. On my 1983 750 it goes from the main fuel tank to the sub-fuel tank.

 

[93gc40]

Those are BOTH vents and should be open to air, NOT PLUGGED.

 

[SteveSchu]

Think of it like the air VENT cap on any can of gasoline. Try pouring the gasoline out with the vent closed, then with the vent opened. Or a bottle pourer that you see stuck in liquor bottles in the bar. The bartender holds his finger over the vent hole to stop the flow of alcohol into your appletini.

 

[Scrapdog2grand]

my tank vents in a different location on the tank, but still same function.
the other is the carb bowl vent. and they both should be vented to atmosphere.

 

[shadowmac83]

thanks for everyones help.