Fuel gage to empty when bilge pump on

[ogibbs]

Hi need some help please. When I switch bilge pump on fuel guage drops to empty as if no power is getting to guage.
When I turn the bac lights switch on (nav lights currently not working) the fuel guage rises a little bit?

Left rather confused? Any ideas ?

[gnrphil]

Check your ground wires, if necessary get a spool of automotive wire and run a new ground to test.

[gnrphil]

And   aboard.