Thank you everyone for your input,Denny,thank you for the schematic and 'edumacation'.
I had an idea the circuitry itself was fairly basic and like you mention the gauge and sender came as a kit and therefore should be matched.
I have a ground (thoroughly checked) directly from the sender to the rear of the cab,and from what I read a second ground from the sender to the gauge wouldn't hurt?
The tank is brand new aftermarket and has no internal obstructions or baffles and the sender orientation hasn't changed either since its initial installation (and did work) so the float definitely isn't contacting anywhere within its arc of travel.
