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Upgrading lift pump system

Discussion in 'All Other Diesels' started by gmctd, May 7, 2008.

  1. gmctd

    gmctd Diesels, Anonymous

    May 3, 2008
    Problem being - the long Dodge fuel tank is mounted longitudinally in the chassis, with the fuel tank module mounted about halfway center - this is good for cornering, but when accelerating or decelerating at low fuel levels, the fuel will slosh to either end of the tank, uncovering the fuel pickup and allowing the lift pump to draw air into the fuel supply system - engine power tends to drop on a diet of injected air, said air being much less flammable than the expected fuel.

    So - for those '03-'07 CRD Diesels experiencing fuel starvation at ~1/4 tank with the aftermarket high output lift pump systems and the multiple hole drillings amongst the fuel tank, here is a solution -

    '06 Dodge module on left, '05 Jeep module on right - ignore black gasket from '04 Dodge Durango, both modules use o'ring seal




    The '05-'06 Jeep KJ CRD Diesel uses the Bosch CP3 injection pump in the draw-from-tank mode - 'nuther words, there is no auxiliary lift pump installed in the fuel module in the tank - it is simply a strained fuel pickup and fuel return assembly, with fuel guage sender.
    It is designed internally to eliminate foaming and aeration at the pickup point, and to supply fuel until the tank is empty - and it does so in the Jeep.

    The beauty of it is, it is identical to the Dodge Cummins in-tank lift pump module, incl the fuel guage sender module - everything is identical: size, shape, electrical connector, fuel supply and return lines, and color - but the Dodge gets a pump, the Jeep doesn't.

    Now - if the unused Dodge lift pump module was removed, and the Jeep module installed in it's place, your fuel supply and return problems would be solved, as the module is engineered for remote, outside the tank, lift pump service - no bubbles, no air pockets, no starving for fuel, no running out of fuel B4 the tank is MT.

    How does the fuel basket fill up and stay filled with fuel with no lift pump?

    Good question - it's simple Science 101 - the CP3 has a very powerful draw-type lift pump, pressure-regulated, excess output bypass feeding a return line into the cup - when fuel volume is lower in the cup than the level outside in the tank, the greater mass of fuel outside forces the flapper valve in the bottom of the cup open, allowing the liquid to seek it's own level, thus equalizing inside\outside level - also has help from the return line in maintaining that inside level, again based on the weight of the fuel inside the cup vs that outside the cup as tank level drops.

    Same thing happens when the fuel inside is foamy - liquid fuel has more mass - greater weight - than foamy fuel: the level will equalize

    'Nuther words, yer cup may have a nice head on it, but it'll be a cup full of fuel, eh?

    Thus the cup level is always more than sufficient to keep the pickup intake submerged and 'wet' down to MT tank - "E" on your guage

    If you're concerned about hot return-line fuel effecting power loss, just add a cooler to the return-line to lower fuel temps to ambient - DeRaille has some nice fan-over coolers, or create your own from summitracingdotcom, etc.

    You will need to increase supply-line size as you head toward 900hp, but the module will still function - should be no hill to replace the 3/8" oem line with 5/8" bulkhead fittings to increase line diameter to the pickup

    Whadda deal - and all for only $96bucks at yer local fuel module emporium.

    Try it - you'll like it................[​IMG]
    Last edited: Nov 26, 2008
  2. hoot

    hoot Recruit

    May 10, 2008
    SE PA
    I'll have to remember that if mine ever needs replacing. Good stuff! How in the heck did you find this out?
  3. gmctd

    gmctd Diesels, Anonymous

    May 3, 2008
    That's what I do, Hoot - on the flip side, there is a steadily increasing number of Jeep CRD's running around with a Dodge Diesel lift pump, solving the fuel starvation problem in the Jeep - those pics are from R&D on my son's Jeep - seeing repeat posts on similar problems with the FASS and AIRDOG and other installations running out of fuel at 1/4 tank on the Dodge forums prompted this post with pics, and the ever increasing number of Dodges with Jeep fuel modules - was neat to find in-house solutions for two separate vehicle lines in one fell swoop, eh............
  4. TIM Z

    TIM Z Tie Rod Bender

    May 7, 2008
    Navarre, Ohio
    Wow, great info for dodge guys! I'll have to tell the cumminGs guys at work.
  5. gmctd

    gmctd Diesels, Anonymous

    May 3, 2008
    They've already seen it if they've browsed any of several Dodge forums................
  6. 05_CTD_CalebS

    05_CTD_CalebS New Member

    May 17, 2008
    West Lafayette, IN
    That is some good info to know...thanks!

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