Re: fuel pump wiring & relay.
by your use of the switched positive term, I take it your a spark like me? Thinking about it, if the pump is a single speed 2 wire motor then one wire has to be the feed and the other the return, and since all car power must return to earth then thats the only thing it can be.
I take it the pump has another (switched live) wire already attached and this black is the second wire coming OFF the pump?
If it is, and you turn on the ign you should get a voltage of less than vBat between the black wire tip and ground on a meter, showing the voltage drop across the pump impedance and confirming the black as a ground. The other wire will be at full vBat to earth. (no one carries an earth wire to a car component when the whole body is an earth return, you would just ground it locally unless there is no access to the grounded metalwork - so as such the tank itself may not be grounded at all and have rubber mounts so they might have run an earth to the pump from the car in that case - OR there maybe should be a body earth strap to the tank itself and its broken)
If it was a full switched live wire it would spark so bad you wouldn't try grounding it again and would have blown a fuse lol, if the pump runs with it grounded then it can only be a ground and you could connect it to any point on the main bodywork. The proper earth tags are inside the boot near the rear - under the trim, but any clean earth point would do.
Me & Her...
I love my tractor so much, If it wasn't an abomination o' god's law, I'd make it my wife...
Last edited by evilscotsman; 14-10-07 at 01:21.