Needle still straight up!

[paulheymeson@xxxx]

For all who read my last post.
I have had my dad move the wires to the sender and multiplug with me 
sitting inside and no different on the gauge.
So I was wondering as my fuel gauge does start working again then not 
i.e if you go over a bump in the road,perhaps it's a bad earth?
Does anyone know which wire of the 3 is the earth and where does it 
end up?
If it leads to a bolt on the frame I could clean It up.

Many Thanks.

Paul.Vin 741.