External fuel pump retrainer plate, o ring needed?

[Superjustin13]

So i was putting together my external fuel pump today. finishing assembly and i put my O ring on my retainer plate and starting putting it in, apparently i accidently pinched it! YAY! brand new 13$ Seal and 25$ retainer plate. Anyways i removed the Internal fuel pump and run an external one. Is this seal even really needed?