[nu2-72]

If there is still a faint smell of fuel, I would #1 remove tank to an outdoor location. #2 Use a shop vac to blow air into the tank and purge it of all fumes. ( do not vac fumes out as you do not want fumes in the vac canister where sparks may occur during startup) #3 you can then purge the tank with a non flammable gas like nitrogen or CO2. If you are wire welding, filling the tank with CO2/argon mix is welding gas anyway. Use low pressure so as not to effect the weld, just keep the tank clear. #4 ask more people, this is my experience and more input is always better. Good luck.