Secondary (booster) pump

I have a 99' supra with 350 CID MPI. The fuel line runs from the tank, through a carter fuel pump, through the fuel/water separator, then through what looks like a secondary fuel pump then through the rail and fuel filter and into the engine. My question is regarding the secondary fuel pump. Are these common on those engines. It almost looks as if it was added after market as the wires that supply power to the carter pump are spliced and ran through a relay then to the secondary (booster) pump. Any help is greatly appreciated as I believe this pump has gone bad.