Checking for air in Cat fuel return

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by w9l, Aug 9, 2020.

  1. w9l

    w9l Medium Load Member

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    Oct 12, 2013
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    Wanting to do this on a c mechanical with FASS on it and on an Acert that has been 6nz'd. Done it with clear hose strung up over mirror bracket. That was on a b mechanical but I can't remember how I plumbed it. Do you just unhook return off top of injection pump and plumb the clear hose inline there? I know there is a restriction orifice in the Male jic fitting there. Seems like that could cause bubbles?
    What about the C15? Where do you plumb clear hose into on it? Changing all lines from tanks forward and have fuel sweeping at splitter and lines are damp with fuel. Would like to compare before and after. The C15 has a rough running flutter in it that no one has cured in 200k miles. Did it when it was an Acert with compounds and still after inframe with industrial cyl packs, 6nz head, 1496988, etc,etc. Fuel lines are one of the only things left common before and after.
     
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  3. swaan

    swaan Road Train Member

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    If there weeping fuel there at splitter on top transmission then your sucking air.

    I would just fix it. And if it runs better then you know .
     
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  4. BoxCarKidd

    BoxCarKidd Road Train Member

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    So start with air in fuel and pressures.
    The one I saw doing strange stuff like that ended up being wiring to a crankshaft sensor.
    I was not the finder or fixer but just sharing.
     
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  5. w9l

    w9l Medium Load Member

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    Oct 12, 2013
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    Definitely gonna change splitter and what hoses I have time for today. The C model has a slight flutter in exhaust also. It is minor enough I doubt if most would notice it. With the FASS holding steady pressure at 58 psi at secondary filter I doubt it is air - at least from supply. Thinking it may be a b&p issue since it has the ones that don't seem to last very well when lapped. Have a brand new set of 6 I need to install.....
     
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