On a 87 z28 the electric fuel pump plug has a black wire an gray wire black to the tube an gray wire to the plug of the pump this is the part the goes inside the tank. on the top of the pump you have a black ground purple gauge an gray power Iam not using the ele. pump no more I took it out because it is a carb. car. Iam going to use a electric holley pump which wires can I get rid of. Thanks

 

The grey wire is power from the pump relay, the blk is ground and the purple is for your fuel level sender.

 

are you using a external electric fuel pump? if so u wont need any of the wires from the tank. but my advice would be go with a manual fuel pump. i had all kinda trouble with a electric fuel pump when i did my motor swap.not to mention if u use a external electric fuel pump u will most likely need a regulator. plus a holley external pump is well over $100. a good high quality manual pump is half that and no wires at all to deal with and u wont have that aggrivating constand hummm sound from the electric pump.. just my opinion because i have been there. good luck.