328 fuel pump check valve question

I completed my timing belt change without incident. Started it up, took it for a spin and when I returned I noted that I had fuel dripping from the check valve copper washers which stopped when the car was off. Unfortunate coincidence.

I have a new check valve and copper washers. My question: Is it necessary to drain the tanks to change out the fuel pump check valve? My tanks are almost full and it will be a pain if I have to drain them.