KE35 fuel tank leak

[crispy'86]

I have put a 2tgeu in my car running E.F.I. it's been in for around a week and i have noticed that the fuel tank is leaking around the fuel gauge sender unit. I am still using the original tank and swapped the lines for the E.F.I. pressure line and using original for the return to the tank. Any ideas how i could get rid of the leak, i was thinking sealing around the sender unit or run a bypass from the tank when it's too full, don't need a surge tank as the car doesn't have any problems with fuel starvation when the fuel level is low.