I am swapping from a 3.0 to a 4.0 and noticed the 4.0 has a fuel return line. I asked Ford about this and they said it is used for pressure to injectors.

I am wondering what I need to buy and do so this will be set up for the 4.0 to be used in the truck. Any information will help with this.

Thanks.

 

One is a return-type system with the pressure regulator on the fuel rail; the other is returnless with the regulator in the tank. The two systems run at very different pressures and require different flowrate injectors. You must match the pump/lines/regulator/ injectors/fuel rails/PCM from a compatible donor or it won't work.

A 98+ 4.0L will be returnless like your 3.0L but this type of swap is still a minefield of potential problems. Staying with the same year donor as your truck is the best way to avoid compatibility issues.