Does anyone know what the fuel pressure should be in my 2004 4.0L auto,4WD super cab ranger? Its reading 50psi @ 700rpm drops off to 45 psi @ 3000 rpm. The truck has been throwing up PO 171 and PO 174 code for a couple months now.I have checked and rechecked for vacuem leaks.Code pops up under hard acceleration.New fuel filter,air filter,new mass airflow sensor. PCV valve? None! Ford didnt put one on this truck.Just a tube! I took the one that is supose to fit and modifided it so it would seal.It made no differance. The right bank hot O2 sensor has low output. .2v/.3v compared to .6v on the left side. Left side LT fuel trim % is high. Im open to feed back here. Thanks, RT

 

If you do not put it on a smoke machine, then you have not really checked for vacuum leaks. My guess is you have a bad vacuum leak.