Ive done some searching and there seems to be a lot of conflicting data on weather or not late model F series have return fuel lines. Some say yes, some say no. According to the local ford parts department 2001-2003 4.6L and 5.4L both have return fuel lines. Why is there so much confusion on this issue?

 

My 01 4.6 has a return system. I believe that they are found on cars such as the Mustang. Easy way to check is look for a fuel pressure regulator on the injector rail. Most have a red vacuum line to them.

 

HI!... Well my truck is a "99" and has a return set-up on it and it has a RED vacuum line going to the stock fuel pressure regulator. My buddies "2002" F-150 also has the samw set-up as my truck. Another friend and my brothers father in law have "03" MUSTANG COBRA's and they have a returnless system. Also another friend has a "2002" MUSTANG GT and it has a returnless system. I don't know if the trucks are set up different or not but all three of the above mentioned cars all have a electronic fuel pressure regulator on them. The computer controls fuel pressure electronically over the standard vacuum system.

 

All the '02 and up cars are returnless.

The PCM gets a fuel pressure reading from the fuel rail pressure trandsucer and the fuel pump driver module switches the fuel pump on and off to maintain the required fuel press.