I replaced my fuel pump in my 02 ranger 4.0l 4x4 a couple weeks ago after I replaced it the truck ran good until I went to fill up for the first time on my 8 hour drive home the truck had stalled trying to leave the parking lot started right back up and ran fine until I got onto the interstate when I got it up to speed and set the cruise control it kept jerking forward like the transmission kept kicking in and out of gear ran perfectly fine after the short fit it through until next fill up when it did same thing it’s throwing a code but not when it’s acting up just randomly the codes that I have got so far is fuel system too lean and Evap control system small leak I replaced purge valve no difference come lastnight it had sat all day out in the cold and truck would not idle and acted like it starved for fuel until it finally had got to temp does anyone have any ideas on what it could be thought about replacing fuel pump again maybe I got a bad pump not to sure

 

Have you done a fuel pressure test? Did you clean out the fuel tank when you replaced the pump? Could be a clogged fuel filter. Also, you could check the motor integrity using a digital amp clamp and PicoScope software. All this is pretty inexpensive. What led you to replace the old fuel pump?

Just checked the PSI specs on my 99 4.0. Manual states: 441 kPa plus or minus 55 kPa, or 64 psi plus or minus 8 psi. In addition, my 99 uses what the manual refers to as a MRFS or mechanical returnless fuel system. For this to work the fuel pressure regulator needs to be in the fuel tank at the pump. Could be that yours is bad. The regulator that is. There is a video by 'stutzman' where he diags a Ford, Crown Vic return-less system. Worth watching.

Good luck and keep us posted.

 

Sorry, just saw all those attachments you had with the lean codes on bank 1 and bank 2. Probably would have been easier for all of us if you had simply posted the codes without the pics. Just saying.

Anyway, lean codes can mean a whole host of things. Perhaps by now you have figured some things out. But, lean codes can be un-metered air after the MAF sensor. Could also be a ditrly MAF sensor. Lots of videos out there about MAF and lean codes. Does sound like you have vacuum leaks but this is only a major problem at idle. How does it idle?

It does seem odd that it ran fine until you filled it up. Strange. What could have changed? Hmm...?