Still fuel leak! errr

ok pulled my tank... then found the leak, which was a bad o-ring around the fuel guage sender... replaced the o-ring (had to get one from a junk yard) put tank back up... didnt leak for 2 days! now its leaking today

question is i forgot to put a hose back on! Yes i know!!! i don't know how the hell i forgot to but i did its the one that connects to a plastic thing next to the fuel pump! could that be the problem?? whats its function? yesterday i order new o-rings and locking thing just incase thats still the problem??? Anyone think its my tank? should i replace that?