2014 f250xa

[Masonmobilemarine]

Can I do this with no power applied or with batteries on and key in on position? I ordered the Yamaha service manual but won’t receive it for a week or so

yes, no power needed. It's just a big carb float bowl.

[TownsendsFJR1300]

Can I do this with no power applied or with batteries on and key in on position? I ordered the Yamaha service manual but won’t receive it for a week or so

As noted above, no key on. Just loosen the screw and let gravity do the work or prime the bulb and help it along..