fuel sending unit leking

[bigeasy1]

I meant "Leaking", not leking

Who's the rocket scientest that decided to use sheet metal screws instead of machine screws to hold down the face plate of a sending unit on a gasoline fuel tank.?
My last sending unit failed so I replaced it with a new Wemu unit that works great.However,when I fill the tank to capacity(55 gals),gasoline leaks out of one of the sheet metal screws used to hold down the plate.It doesn't leak around the gasket,it leaks past the threads on the screw.
It's not a huge amount,but its enough to smell up the boat,and definitely not safe.This only happens when I fill the tank to capacity.
The leaking stops once a few gallons are used.
With only a 55 gallon capacity,its important to have as much fuel as necessary to make needed trips to fishing areas.
I have tried everything to stop the leak but most sealers don't work.
Why wouldnt the builder use studs instead of screws?with all sending units being mostly standard, studs would seem to make sense.,that way you could tighten it down with nuts.
Anyone have any ideas or know of a sealer to remedy this problem?