Put it in a bench vice, with a full fuel line ( might need it siphoning down from a can, to put more psi on it) & hold the float up & look to see where the fuel's leaking by, at
Your cap is venting good?
Cant remember if floats are the same, but swap & see if problem follows.
Put fuel in your bowl too & let it sit, o f tube might be cracked down low.
Bowls are different you can swap them to leak test but not run on.