Fuel Pump Issues

Discussion in '2005+ Mustang GT 4.6L Tech' started by Shawn Fellows, Mar 5, 2019.

  1. Shawn Fellows

    Shawn Fellows Junior Member

    Have an 05 GT heavily modified, with GT500 dual pump system. Car will crank and drive at times. Then fuel pump shuts off and car dies. Sometimes can wait a few minutes or sometimes its hours before the pump will work again. Already tried to replace both the FPCM, also swapped out the relays under the hood, PCM#1, PCM#2, and Fuel pump relay.
    Any suggestions?

  2. golkhl

    golkhl forum member

    Bad ground?
  3. saleen836

    saleen836 forum member

    Sounds very similar to problems I had running GT500 dual pumps in my supercharged Saleen, car would be fine for days/weeks then would suddenly just not fire, leave it a few hours try again and it would fire and run as if nothing happened, replaced the FPDM's checked all connections/wiring couldn't find a fault, was out driving one day came off a roundabout and car just had no power then died, it did re start but lumpy idle and a soon as I pressed the gas pedal it would die, transported the car home removed the pumps re installed the standard pump and added a Kenne Bell BAP and not had a problem since in the 6 years since doing so
  4. eighty6gt

    eighty6gt forum member

    pumps are ground switched via FPDM.

    check for 12+ at the power supply to both pumps, comes straight from the forward relays.

    check for ground supply to FPDM.

    Could also be a dead pump!
  5. 06monera96

    06monera96 LeShawno

    This is a long shot but
    The relay in the BEC likes to get hot and the blade pin beneath the plastic would start to spread further than tolerance.
    Once it heats up 1 of the legs on the relay would lose contact thus turning off the injectors and pump.

    The 2nd issue would be corrosion at the connectors by the passenger kick panel.
    I found that water leaks down from 2different spots ( window cowl and fender into the wire loom and start corrosion at this connector)

    The 3rd issue could be that the wiring has started to "rub" against the fuel tank on the left side and you may have lost ground, or return feed to pcm.

    Last PATS is killing fuel pump for some odd reason (pats not sensing key)
  6. Hellionturbo

    Hellionturbo Junior Member

    Hey Shawn did you figure out what the problem was?
  7. 06StangGT

    06StangGT forum member

    For those who had problems with the GT500 dual pump setup, were you using the GT500 pumps or aftermarket pumps?
  8. saleen836

    saleen836 forum member

    I had Ford GT500 dual pumps installed in mine (they failed)
  9. 06StangGT

    06StangGT forum member

    I bought two DW300M pumps to run in the Gt500 fuel hat-per the man, Lito. I will be installing this week, hoping for the best.

    Sent from my iPhone using Tapatalk
  10. nfrizell

    nfrizell Member

    I just changed my fuel filter as a precautionary measure before data logging with my tuner. It was full of crap and my fuel delivery issues all but vanished. It was going lean up high and it was flakey at tip in.

    Sent from my SM-G930V using Tapatalk
  11. Midlife Crises

    Midlife Crises Junior Member

    I was running the GT500 dual fuel pumps. One of them failed so I replaced them with the DW300 direct replacement set. I also repaired a few bad electrical connections and my fuel delivery problems are solved. Data log shows idle fuel pressure at 39 and duty cycle at .13. The same log shows fuel pressure up to around 60 and duty cycle about .45 at 6,000 wide open. The little spike between shifts shows 75psi and .7 duty cycle.
  12. 06StangGT

    06StangGT forum member

    This is reassuring as I was maxing out the duty cycle around 5000 RPMS on this new build. Will be getting the pumps in this weekend I hope and will be able to start data-logging again.