855 no boost. No power

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Foreverred, Mar 10, 2018.

Page 1 of 7
  1. Mar 10, 2018 #1
    Foreverred

    Foreverred Bobtail Member

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    Mar 10, 2018
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    Hi all, needing some help have a big cam formula 350 in a truck. Cannot get any power out of it. Builds 10 lbs boost on a good day. Looking for new ideas to look for. Here’s what I’ve done so far:
    New pt pump a year ago by certified shop. Rebuilt and supposed to make 425 hp.
    -checked turbo, spins freely, no chips out of turbine or compressor. Very minimal play.
    -put regulated air to aftercooler. Could get a some air out of blow by tube but didn’t seem excessive. No other obvious leaks.
    -checked line from aftercooler to afc on pump for obstructions. Blew into afc to make sure diaphragm didn’t leak.
    -replaced pickup tube in tank as well as supply lines.
    -had overhead ran and new injectors a year ago.

    If anything comes to mind to check out please let me know. Any help is appreciated.
     
    Foreverred, Mar 10, 2018
    Foreverred, Mar 10, 2018
    #1
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  3. Mar 10, 2018 #2
    AModelCat

    AModelCat Road Train Member

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    When was the last time you put new air filters in?

    Did you check the intake piping between the turbo and intake manifold for leaks?

    Is the exhaust free of restrictions? A plugged up exhaust is just as bad as a restricted intake and has pretty much the same effect.

    Fuel filters/fuel supply: No fuel, no power. If the fuel lines are getting up there in age they can collapse internally and restrict fuel flow. Any loose fittings or connections on the suction side can also allow air in.
     
    AModelCat, Mar 10, 2018
    AModelCat, Mar 10, 2018
    #2
  4. Mar 10, 2018 #3
    BoxCarKidd

    BoxCarKidd Road Train Member

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    Reluctant to reply. Have you used the search block at the top right?
    After using that myself I will share a little bit. If you search "RTLO16410B air leak question Feb 2 2017" is a picture of the tool in the day. Maybe someone knows how to move it over here.Today it is just a handy gauge set for miscellaneous stuff.
    Start here: Does the fuel pump lever brake over? Does it ever surge and or return it idle slowly? If so likely sucking air in fuel inlet lines. Need to know what the rail pressure is under load. A gauge in the fuel shut off solenoid plug can tell that if you put it where you can read it while driving. Used to use a radiator pressure tester plumbed to the AFC at 20 PSI. Does it loose pressure or preform different driven pumped up? Other common tests were a clear hose to check for air in the suction hose. A vacuum gauge on the pump fuel inlet. Some times the fuel solenoid can restrict fuel.
     
    BoxCarKidd, Mar 10, 2018
    BoxCarKidd, Mar 10, 2018
    #3
    KB3MMX Thanks this.
  5. Mar 24, 2018 #4
    Foreverred

    Foreverred Bobtail Member

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    Mar 10, 2018
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    Ended up the aneroid plunger was stuck. Even when we added 30 psi to afc it didn’t run better. Was only building 50 psi to the rail. Removed tin cover and backed fuel screw out a few turns and got 190 psi to the rail again. Taking it to pump shop to get the whole aneroid system basically deleted and have them set it up without it. From talking to our pump guy he said it’s easily done. Thanks for the help guys.
     
    Foreverred, Mar 24, 2018
    Foreverred, Mar 24, 2018
    #4
  7. Jan 9, 2020 #5
    gleisom79

    gleisom79 Bobtail Member

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    Jan 9, 2020
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    Hi Guys I have no idea how to create post here I’m new to this,I just purchase Freightliner with Cummins big cam 350 replace air filter fuel filter new fuel pump new turbo and I’m getting 28psi turbo pressure 3.5mpg with 100.000 no torque no much power is anything you guys can help me to make this truck running right
    Thanks
     
    gleisom79, Jan 9, 2020
    gleisom79, Jan 9, 2020
    #5
  8. Jan 9, 2020 #6
    Roberts450

    Roberts450 Road Train Member

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    350 hp pulling 100,000 pounds sounds about right. What RPM are you pulling at?? Hopefully 1700+ RPM
     
    Roberts450, Jan 9, 2020
    Roberts450, Jan 9, 2020
    #6
    magoo68 and BoxCarKidd Thank this.
  9. Jan 9, 2020 #7
    BoxCarKidd

    BoxCarKidd Road Train Member

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    There has been a lot of info here for low power on NTC's. The search block is at the top right. Ask your questions in different ways. There are basic things to test or have tested.
    As stated: Sounds about right.
     
    BoxCarKidd, Jan 9, 2020
    BoxCarKidd, Jan 9, 2020
    #7
    spsauerland Thanks this.
  10. Jan 9, 2020 #8
    gleisom79

    gleisom79 Bobtail Member

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    Hauling heavy all the time and truck doesn’t respond well not lot torque,slow respond,lost power and is hard to make 65 mph
     
    gleisom79, Jan 9, 2020
    gleisom79, Jan 9, 2020
    #8
  11. Jan 9, 2020 #9
    gleisom79

    gleisom79 Bobtail Member

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    Hi I read lots stuff here for BC then get new turbo replace button change air filters hoses and for me doesn’t running right.
    All mechanic near by don’t even want look
     
    gleisom79, Jan 9, 2020
    gleisom79, Jan 9, 2020
    #9
  12. Jan 9, 2020 #10
    gleisom79

    gleisom79 Bobtail Member

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    Jan 9, 2020
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    Yes rpm is about 1700
     
    gleisom79, Jan 9, 2020
    gleisom79, Jan 9, 2020
    #10
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