Originally Posted by 04F150
I need to do a fuel pressure test on my 2004 F150 with the 5.4L.
Is there a designated place to hook up a pressure tester? I looked around the fuel rails and didnt see anything. Also what should my pressure be? I am getting lean codes and cant seem to locate any vac leaks using a can of carb cleaner. I just changed the fuel filter and the problem still exists so I am guessing low fuel pressure from the pump or a vac leak I didnt catch.
One of the fuel rails, usually on the passenger side towards the rear, should have a Schrader valve stem on it. That is the fuel pressure monitor port.
Fuel pressures should be: Engine Off, 30-45psi
Engine Running, 27-42psi.
The pressures can be anywhere within these limits; if close to the lowest rating the PCM will know what to do and compensate by holding the injectors on slighty longer. Injector problems usually are not the culprit causing lean mixture readings; instead look for vacuum leaks, tank pressure/evap system troubles or bad HGO sensors.
And good luck trying to find room to work under that @#$%!! hood.