'99 Explorer Fuel pressure problem

Question:

I’ve been doing some troubleshooting on my Explorer recently.  It suffers from the hard to start problem as many others do.  Sure enough, I found that the fuel rail pressure bleeds to zero almost instantaneously after it’s shut off.  The other interesting thing is that the fuel pressure reads 64PSI at all times when running, with or without the vacuum line to the FPR hooked up. So, it sounds like my FPR is stuck closed (causing the pressure to go to 64PSI) AND the fuel pump is faulty allowing the pressure to bleed back into the tank through the supply line.  Has anyone ran into this problem and it only be the FPR?  It seems unlikely.  It doesn’t seem possible that the fault lies solely in the fuel pump. My next step is to: 1. Double check the fuel pressure with another gauge. 2. Double check the idle fuel pressure spec.  The Haynes could be wrong. 3. Replace the FPR and see what happens. 4. Replace the fuel pump if (3) doesn’t fix it. 5. If that doesn’t work, give up. On a side note, the truck never really runs poorly from a drivability standpoint, just hard to start, and intermittently down on power.  Hopefully there isn’t some other issue. Any help is appreciated.

Response:

In case anyone is following this, I’ve learned the hard way that my Explorer fuel pressure (at idle) is supposed to be from 56 to 72PSI.  The Haynes manual and Mitchell professional books (at the library) both state around 40PSI at idle for the Explorer.  For certain years of the Ranger 4.0l, they list 56-72PSI.  That apparently is what mine falls under.  The "Motor" repair manual (at library) did state the 56-72PSI.  Not sure what All-Data lists.  Lesson learned, Haynes manuals stink. The other reason I know this, is that I purchased a brand new FPR from Ford and it reads exactly the same, a rock steady 64PSI at idle. FYI, my Explorer is a ‘99 Sport, 2WD, OHV, 5spd manual.

– Hide quoted text — Show quoted text -> I’ve been doing some troubleshooting on my Explorer recently.  It suffers > from the hard to start problem as many others do.  Sure enough, I found that > the fuel rail pressure bleeds to zero almost instantaneously after it’s shut > off.  The other interesting thing is that the fuel pressure reads 64PSI at > all times when running, with or without the vacuum line to the FPR hooked > up. > So, it sounds like my FPR is stuck closed (causing the pressure to go to > 64PSI) AND the fuel pump is faulty allowing the pressure to bleed back into > the tank through the supply line.  Has anyone ran into this problem and it > only be the FPR?  It seems unlikely.  It doesn’t seem possible that the > fault lies solely in the fuel pump. > My next step is to: > 1. Double check the fuel pressure with another gauge. > 2. Double check the idle fuel pressure spec.  The Haynes could be wrong. > 3. Replace the FPR and see what happens. > 4. Replace the fuel pump if (3) doesn’t fix it. > 5. If that doesn’t work, give up. > On a side note, the truck never really runs poorly from a drivability > standpoint, just hard to start, and intermittently down on power. Hopefully > there isn’t some other issue. > Any help is appreciated.

Response:

Anything you find on this would be a help.  Mine does the same thing.  Hard starts and low power.  I’ve always suspected the fuel pump, but it runs fine after it starts.  I’m still thinking it may be a vacuum problem.

– Hide quoted text — Show quoted text -> In case anyone is following this, I’ve learned the hard way that my > Explorer > fuel pressure (at idle) is supposed to be from 56 to 72PSI.  The Haynes > manual and Mitchell professional books (at the library) both state around > 40PSI at idle for the Explorer.  For certain years of the Ranger 4.0l, > they > list 56-72PSI.  That apparently is what mine falls under.  The "Motor" > repair manual (at library) did state the 56-72PSI.  Not sure what All-Data > lists.  Lesson learned, Haynes manuals stink. > The other reason I know this, is that I purchased a brand new FPR from > Ford > and it reads exactly the same, a rock steady 64PSI at idle. > FYI, my Explorer is a ‘99 Sport, 2WD, OHV, 5spd manual. > I’ve been doing some troubleshooting on my Explorer recently.  It suffers > from the hard to start problem as many others do.  Sure enough, I found > that > the fuel rail pressure bleeds to zero almost instantaneously after it’s > shut > off.  The other interesting thing is that the fuel pressure reads 64PSI > at > all times when running, with or without the vacuum line to the FPR hooked > up. > So, it sounds like my FPR is stuck closed (causing the pressure to go to > 64PSI) AND the fuel pump is faulty allowing the pressure to bleed back > into > the tank through the supply line.  Has anyone ran into this problem and > it > only be the FPR?  It seems unlikely.  It doesn’t seem possible that the > fault lies solely in the fuel pump. > My next step is to: > 1. Double check the fuel pressure with another gauge. > 2. Double check the idle fuel pressure spec.  The Haynes could be wrong. > 3. Replace the FPR and see what happens. > 4. Replace the fuel pump if (3) doesn’t fix it. > 5. If that doesn’t work, give up. > On a side note, the truck never really runs poorly from a drivability > standpoint, just hard to start, and intermittently down on power. > Hopefully > there isn’t some other issue. > Any help is appreciated.

Response:

I found that the system is mechanical returnless one.  The relief valve in the tank (part of the fuel pump assembly) is leaking by.  Stopped by the dealer today, the only way to replace it is to buy the entire assembly which is about $350.  The local parts store has them for about $210.  I’m going to buy a used one from a salvage yard for $28 and give it a shot.

– Hide quoted text — Show quoted text -> Anything you find on this would be a help.  Mine does the same thing. Hard > starts and low power.  I’ve always suspected the fuel pump, but it runs fine > after it starts.  I’m still thinking it may be a vacuum problem. > In case anyone is following this, I’ve learned the hard way that my > Explorer > fuel pressure (at idle) is supposed to be from 56 to 72PSI.  The Haynes > manual and Mitchell professional books (at the library) both state around > 40PSI at idle for the Explorer.  For certain years of the Ranger 4.0l, > they > list 56-72PSI.  That apparently is what mine falls under.  The "Motor" > repair manual (at library) did state the 56-72PSI.  Not sure what All-Data > lists.  Lesson learned, Haynes manuals stink. > The other reason I know this, is that I purchased a brand new FPR from > Ford > and it reads exactly the same, a rock steady 64PSI at idle. > FYI, my Explorer is a ‘99 Sport, 2WD, OHV, 5spd manual. >> I’ve been doing some troubleshooting on my Explorer recently.  It suffers >> from the hard to start problem as many others do.  Sure enough, I found > that >> the fuel rail pressure bleeds to zero almost instantaneously after it’s > shut >> off.  The other interesting thing is that the fuel pressure reads 64PSI >> at >> all times when running, with or without the vacuum line to the FPR hooked >> up. >> So, it sounds like my FPR is stuck closed (causing the pressure to go to >> 64PSI) AND the fuel pump is faulty allowing the pressure to bleed back > into >> the tank through the supply line.  Has anyone ran into this problem and >> it >> only be the FPR?  It seems unlikely.  It doesn’t seem possible that the >> fault lies solely in the fuel pump. >> My next step is to: >> 1. Double check the fuel pressure with another gauge. >> 2. Double check the idle fuel pressure spec.  The Haynes could be wrong. >> 3. Replace the FPR and see what happens. >> 4. Replace the fuel pump if (3) doesn’t fix it. >> 5. If that doesn’t work, give up. >> On a side note, the truck never really runs poorly from a drivability >> standpoint, just hard to start, and intermittently down on power. > Hopefully >> there isn’t some other issue. >> Any help is appreciated.

Response:

Hello: I’m working on the same vehicle with the same problem and have replaced the fuel pump already. However that did not fix the problem. Fuel pressure still bleeds down causing hard start. While I was replacing the pump I noticed a valve looking thing directly above the fuel pump in the line. Looks like a return valve or something it has a hose that comes off of it back into the tank. Did you replace that also? and do you think that could be my problem? Nothing else is tied into the fuel line except that and the injectors. I suppose I could have an injector leaking down. Please let me know if you replaced that valve, what it may be or if you have any other thoughts on this. Thanks in advance.

Response:

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