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Help Fuel pump issue driving me crazy


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Hey guys I am new here and really apreciate any help or tips given. My wifes 04 Cayenne S owned since new has gone through just about all of the common isuues known (coolant pipes, coils, drive shaft, rear main sea) and many more things in between to long to list. I just had the common stalling issues due to faulty fuel pumps or pump, what I decided to do was have all changed both fuel pumps and fuel filter. A week or two later car hit a1/4 quater tank of gas stalled again. I brought the car back to my mechanic who is great he did a check of the pumps and noticed that the passenger side pump only stays on for ten seconds when it should really stay on full time when the car has a 1/4 tank or less of gas. All relays and fuses are ok as well as sending unit . He seems to think that it could be a fuel leveling sensor.

Basic breakdown. 1/4 tank or less car stalls out it has new pumps please help

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The right side fuel pump is only on at certain times and never runs full time. Are you sure the cross over pipes to equalize fuel level on each side of the tank are fitted correctly? What is the fuel level in the left side pump module at 1/4 tank?

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The cross over fittings are all fitted correctly to the best of my knowledge. I am pretty sure my mechanic told me that they are all male and female different sized fittings. Basically car runs great until it hits a 1/4 tank then dies out. Should the car stay running when you disconnect the drivers side pump and leave it to run on passenger side, because it stays on but only for about 10 or so seconds. Thank you for your time and help

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  • 2 months later...

The cross over fittings are all fitted correctly to the best of my knowledge. I am pretty sure my mechanic told me that they are all male and female different sized fittings. Basically car runs great until it hits a 1/4 tank then dies out. Should the car stay running when you disconnect the drivers side pump and leave it to run on passenger side, because it stays on but only for about 10 or so seconds. Thank you for your time and help

Would you share with me how you did solve the problem?I got the pumps and filter replaced . runs great in the beginning even the idle drop problem is gone but..... I have the same strange feeling if fuel level goes lower the car is not running smooth. Thank you.
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The cross over fittings are all fitted correctly to the best of my knowledge. I am pretty sure my mechanic told me that they are all male and female different sized fittings. Basically car runs great until it hits a 1/4 tank then dies out. Should the car stay running when you disconnect the drivers side pump and leave it to run on passenger side, because it stays on but only for about 10 or so seconds. Thank you for your time and help

Would you share with me how you did solve the problem?I got the pumps and filter replaced . runs great in the beginning even the idle drop problem is gone but..... I have the same strange feeling if fuel level goes lower the car is not running smooth. Thank you.

It wound up being a faulty secondary pump purchased from the dealer.It was only at certain times car would die out or stutter. I replaced it with another new pump from the dealer all systems clear no issues.

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  • Similar Content

    • By lewisweller
      If I run the car at less than 1/4 tank full it's very smooth great acceleration and responsiveness. With engine running I went and filled up with 99 octane as usual and straightaway the engine stutter comes back!!!!!!!! Fyi it is NOT fuel quality. 
      I've started a new thread for this but it's an old problem mentioned in previous posts and unresolved. 
      Basically the ctt 06 with 114,000km has been hesitating and stuttering for a while when accelerating particularly under boost in lower gears through the rev range of 2k 3k 4k ish rpm, it also will vibrate and stutter revving the same rpm in neutral/park when stationary. (which is very weird). 
      So after a lot of finding issues which helped the car overall none of them sorted this stutter out. 
      Quick list, 
      New oem Coils, plugs, n75 valve, air filters, purge valve, and Dv's,
      Fixed a lot of vac and pcv pipes which leaked 
      Smoke tested intake no leaks boost is +0.8
      Head Gaskets done a few 1,000 km all new parts gasket Seals etc. (problem was present before and after head Gasket work).
       
      I had a suspicion that the lower fuel level was playing a part in this but I can't work out why a fuller tank would cause running issues? 
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