dual tank troubleshooting

[willstruck]

I'm sure this has been addressed a million times, but I searched and didn't come up with anything specific to help me out.

I have dual tanks, one on each side. The guy I bought the truck from said to only use the passenger side tank. He didn't know why, but the guy he bought the truck from told him not to use the drivers side tank. All my vehicles have had the tank on the drivers side, so it annoys me that it's on the wrong side. Plus, at 10mpg, 15 gallons just doesn't get you that far.

I'm basically looking for some troubleshooting steps to try to figure out if the tank might leak, need a pump, solenoid, or something without filling up the tank with gas. I don't need to waste $50 if the tank leaks or whatever, and I lose the gas, or something doesn't work so the gas is stuck in there.