Loss of power/stumble then dies

Discussion in '2nd Gen - 2003 - 2006' started by race4beer, Jul 17, 2017.

  1. race4beer

    race4beer Member

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    Hi,
    Started having an issue with my 03 Expy (5.4 4WD) recently. I've searched and have found a previous thread, but it's very old so I was asked to start a new one.

    Last week I was running about 70MPH when I suddenly had a loss of power and the RPM fell to around 300. There was no throttle response at all, but eventually it came back to life and ran fine. 2 days later the RPMs dropped to about 300 again and the battery light came on. The motor sputtered for about 10 seconds and then died, while it was sputtering, there was zero throttle control. Restarted fine and ran great. Now it's happening a couple of times a day, and each time a restart will clear the issue. Other than the battery light, no other lights come on, and nothing else seems out of the ordinary.

    It's Drive by Cable, and I've removed and cleaned the throttle body and replaced the TPS to eliminate that from being the issue but it's still happening.

    I've read several articles online of possible PCM Issue, Fuel Pump, TPS, grounds, etc but I was hoping to find someone that has had the issue and been able to correct it or at least isolate it to one system.
     
  2. BRIANGEE

    BRIANGEE Member

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    Have you checked for any codes?
     
  3. Bedrck47

    Bedrck47 Full Access Members

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    How many miles on the expy?
    Has the fuel pump ever been replaced?
    Has the fuel filter been replaced?
    Has the fuse box ever been replaced? The fuel pump relay on the fuse box is a common problem with the 03 and 04 expeditions
     
  4. race4beer

    race4beer Member

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    No codes present

    190k, got it with 150k, I don't know for sure what was done before.


    I've done Coils, Plugs, Fuel filter, Intake

    Runs like a champ, then this started out of the blue.
     
  5. docraymund

    docraymund Full Access Members

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    No power means fuel supply was interrupted for a brief moment especially if it occurred after hitting a bump or a pothole. Check wirings pertaining to the fuel pump and see if you can duplicate the problem.
     
  6. Bedrck47

    Bedrck47 Full Access Members

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    From your description of what is happening it appears that the fuel pump relay is beginning to fail

    There is a very good video on you tube




    Pay attention around the 6 minute mark in the video where he is pointing to a dark green/yellow wire.


    This is part of the fuel pump relay contacts There is a way to bypass those contacts to see if your problem is being caused by the FP relay Let me know if you would like that procedure
     
    Last edited: Jul 18, 2017 at 9:09 AM
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  7. race4beer

    race4beer Member

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    Thank you, I'm not dead in the water yet, but I'm at a point where it's dropping out at least once in my commute and making for a pretty scary drive. I think I am going to rig up a small light to the green/yellow and see if when the issue happens I lose power to the bulb (and pump). That green/yellow is the correct power reference to use?
     
  8. Bedrck47

    Bedrck47 Full Access Members

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    yes I am sending you a PM check your in box in a couple of minutes
     
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  9. race4beer

    race4beer Member

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    Thanks
     

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