Fuel shut off valves

ok was checking out my xl and it has a fuel shut off for the right side of the truck. ya I have had some on these trucks before. But my problem is I pulled the small handled bar out towards me to shut the right tank off (this is all from the driver side). need less to say the whole freaking thing came out and I mean the bar that u push in and out. so I looked at the valve where all the lines runs to above the tranny found the little lever and don't remember if the lever sticking up should be pushed towards the passenger side or towards the drivers or in the middle to have both tanks working.

 

so push it all the way down towards the passenger side? and if so I noticed the fuel in the passenger tanks is a bit dirty any type of fuel additive I can get at a truck stop to help this out? and thanks for your help man seems you been a good help since I have joined on this site.

 

brownish its old fuel been sitting some time what about the valves

 

not real black just sort of brownish tinted black

 

lol ya not a bad idea haha might just give it a Kentucky wash when im done