The fuel pump does not always inject fuel. Is it possible for the anti-theft to be connected to the fuel system? Car runs and idels fine but sometimes does not start and do not hear the fuel pump engaging. car will start if left for several minutes or overnite. Just recently the P0171 & P0174 came on but the problem with starting has been in place for several weeks.
problem with starting and fuel pump on 2000 Ford Explorer
by Visitor in Franklinville, NJ on December 18, 2010
ANSWER by DaveJM , December 19, 2010
A couple different things can be going on here. First, your no start with no fuel pump running - you do have a Passive Anti-Theft System (PATS) on the truck that uses a programmed key to allow the car to start when it communicates through a transceiver to a module that recognizes it. If your PATS system is stopping the Explorer from starting, it will allow it to crank, but will not allow fuel pressure, etc. The tell-tale sign on whether PATS is an issue is the THEFT light on the dash. If it is solid on when you put the key in- , then there is no PATS issue. If the light flashes with the key in and in the on position, then you have a system issue or key issue. P0171 - P0174 - bank one and two lean codes - can be caused by a few things. First, if you have low fuel pressure overall, these codes could come on. Beyond that, these 4.0L V6 engines (SOHC version) are known for leaking intake manifold o-ring gaskets, and that will throw the codes. You could also have a mass air flow sensor out of range, or some other vacuum leak. Hope some of that gives you some clues. Write back if you have further questions. Good luck!