Engine Performance problem
2009 Ford F-450 V8 Two Wheel Drive Manual
when the truck is on road the fuel pressure comes down (65psi to 10psi). I replace the fuel filter, and the fuel pump but I didnt know about the variable speed fuel pumps so I decide to use the old fuel pump again and try to find another posible problem, but I am so confuzed.
How can I know if the fuel pump is the problem, maybe the fuel presures sensor or the fuel pressure regulator or could be any fuel pump control module?
plase, a will thak you if you coulg gime me some help.