I have an 87 Z28 with both an electrical fuel pump in the tank and a mechanical fuel pump on the block. My mechanical one just went out (it was a stock one that cost $13). My question is this:
The stock mechanical pump has an inlet, outlet, and an overflow. The overlfow is so that the electrical pump doesnt blowout the mechanical. I am looking for an aftermarket pump to put on. Does anyone know of one that comes with this extra overflow outlet?
Thanks.

 

If the aftermarket pump doesn't come with a fitting for the return line, then it doesn't need one. Don't worry about it.

 

Actually, cars that don't have the electric in-tank pump still have the return line from the mechanical. The purpose is the maintain pressure to the carb via relief valve (much like the oil pump does), returning the excess back to the tank, which has the benefit of keeping cooler fuel going up to the engine.

I have an AC replacement from Checker on mine, and it has worked fine for almost 3 years. I would recommend keeping that setup, rather than going with an aftermarket that doesn't have the return line.