I was just wondering what the proper fuel pressure should be at the fuel rail for a 95 explorer 4.0?

Thank you

Key On Engine Off 35 - 45 psi
Key On Engine Running 30 - 40 psi

Key On Engine Off 35 - 45 psi
Key On Engine Running 30 - 40 psi

how about for a 98 4.0 sohc engine?

30 to 45

30 to 45

the fuel pump that we r using give us 40psi max and 30psi at idle with fuel pressure regulator connected,. it should work ok with that, right? we did a scan to the ecu and gave us the P0171, lean mixture on bank 1, we just replaced all the intake manifold gaskets, no more vaccum lose there,. we thought that might be low fuel pressure, i did the test on the maf, it read 1.5v at iddle and increases to 3 or 5v when stepping on the gas,. we replaced the o2 sensor on that side too, fuel filters replaced already too,.

the facts, engine idles rough sometimes and sometimes it idles 100%ok, sometimes your able to start smoth and sometimes it missfires until it goes above 3200rpms, from 3200 to 5500 everything is ok,. or problems go away if you go wide open throtle from idle,

i recorded this video last weekend, most of the time i was going wot until going above 3200rpms to prevent the missfire ,
http://www.youtube.com/watch?v=aUAmghg9Eh0

fuel injectors clogged, just replaced them and problem solved,. thks, so far so good,. :naughty: