Hi, I have a FX4 5.4l 2004 series (Not Heritage). 140,000 kms. Plugs changed at 100,000kms. Currently I get 24l/100kms or 10mpg on it either mostly city or mostly highway driving. Doesn't change much.

O2 sensors bounce back and forth as they should but the values seem low. .01 to .5 and .6 most of the time which I believe shows a rich state. Bank 2 is the worst and is consistent between the firsts and 2nd o2 sensor. Bank 1 shows .1 to .7 most of the time.

Never throws a code or a check engine light.

It does seem to warm up. Does switch from open to closed loop. ECM is seeing normal operation temp of 90F.

Had at dealer they hooked up to monitor and it shows all within spec. I suspect extra fuel is entering the system. Do these trucks have a fuel pressure regulator. Fordparts.com shows one, but I can't find a diagram of where it is, or if they even have one. if it is leaking and going into the vacuum line could be the source of my issue. I have found reference to a FPDM which is located at the rear and controls the fuel pump. Is that the regulator now?

Thanks for any answers you can provide.

 

You better check the injectors for leakage.

 

Yes, the FPDM controls the fuel pump, there's no regulator.