Bongo Fury

Hi all
I have had problems with my fuel gauge working intermitantly, I have took the carpets out to locate the fuel sender underneath the screw down panel, I have put new connecters onto the terminals but still get a dodgy fuel gauge, it sometimes works & sometimes not at all, I have however noticed that it seems to read the level when the weather is wet! To me this points to a bad earth, but where do I look first?
Thanks for any help recieved.
Roy

You're in the right area Lots have put an extra earth wire at the tank

Now locked due to other thread.