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Fuel System for a 2006 Duramax

Discussion in 'Intakes and Exhausts' started by RI Chevy Silveradoman, May 3, 2011.

  1. RI Chevy Silveradoman

    RI Chevy Silveradoman At your service Staff Member Moderator

    8,671
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    May 3, 2008
    Rhode Island
    I just want to make sure I am understanding the fuel system correctly for my 2006 Duramax. I installed a dual lift pump setup (Kennedy), along with a Nicktane pre-filter setup in the rear next to the fuel tank, as well as the Nicktane setup in the front replacing the OEM filter (Both 2 micron spin on HE filters). While my truck is running at idle, my lift pumps continuously pump fuel through the lines and through the fuel rail. If it is not needed, the extra fuel runs back into the tank, and that makes a continuous circle over and over again. Am I correct in this understanding of how the fuel system works? So in theory, the fuel gets continuously filtered over and over again, constantly running through the filters? Thank you in advance for your help in this fuel related matter.
     
  2. btfarm

    btfarm Quarter Million Worth Staff Member Moderator

    14,874
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    May 12, 2008
    Sandwich, Illinois
    It would seem more likely that the excess from the lift pump would bypass direct to tank which means it only sees the suction side filter.
     
    Last edited: May 3, 2011
  3. Pepperidge

    Pepperidge Member Advocate Staff Member Lead Moderator

    12,093
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    Feb 10, 2008
    Slidell, La
    not sure at what point the excess fuel is returned to the tank...IIRC I believe it is once it passes the CP3 the excess fuel is sent back to the tank...meaning you are using both filters"polishing your fuel...

    The lift pumps really have little to do with excess fuel (but not completely true...it does some now that you've added them) returning to tank but the CP3 is largely responsible for excess fuel volume and pressure causing the unused fuel to be returned to the tank...remember...we didn't come stock with a lift pump and there was excess fuel returning to the tank before adding lift pumps...the fuel is filtered by both your pre-filter(if you have one)and OEM location before going to the CP3...

    so yes Jeff you are correct in your understanding...
     
  4. RI Chevy Silveradoman

    RI Chevy Silveradoman At your service Staff Member Moderator

    8,671
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    May 3, 2008
    Rhode Island
    Thanks. I forgot to throw in there about the CP3. A little Freudian slip I guess. :rof:
     
  5. stacks04

    stacks04 McLovin

    3,579
    0
    May 9, 2008
    terryville ct
    Yes the bulk of the fuel comes back via the pump, the other major contributer is the injector returns. When you doing a throttled run and let off the excess from the injector bodies goes through the return tubes and back. There is no return line pre engine filter. Yes our fuel is very filtered:)
     
  6. RI Chevy Silveradoman

    RI Chevy Silveradoman At your service Staff Member Moderator

    8,671
    75
    May 3, 2008
    Rhode Island
    That is what I was looking for I guess. The fuel gets filtered over and over and over again. Thanks to all for helping me understand the fuel system a little more clearly. :thumbsup:
     
  7. BudTX

    BudTX Edjumacated Redneck

    It gets passed through the filters over and over again, but I don't see any filtration benefit after the first pass through. 3 microns is still 3 microns. Its not like something slipped through the first time and will get caught later, correct?
     
  8. btfarm

    btfarm Quarter Million Worth Staff Member Moderator

    14,874
    368
    May 12, 2008
    Sandwich, Illinois
    The entire surface of the filter media isn't all the same micron level. The rating just means the biggest particle that will pass. Some areas will filter smaller particles so theoretically it could continue to filter out smaller particles that had previously passed through.
     
  9. RI Chevy Silveradoman

    RI Chevy Silveradoman At your service Staff Member Moderator

    8,671
    75
    May 3, 2008
    Rhode Island
    That I am not sure about. I just wanted to make sure that I was understanding the fuel system flow correctly. You're right though Bud. 3 micron is 3 micron. The injectors should pass that fine with no problems. It is the bigger particles that I would be concerned with. The High Efficiency Filters are excellent at doing their job. :thumbsup: When I do my yearly maintenance on June 1st, I will once again, cut open the filters and take a good look at them. It makes me feel better. ;)
     

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