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Thread: Need Help! 2003 Hard Start/No Start

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    Unhappy Need Help! 2003 Hard Start/No Start

    Hey guys, this is my first time posting so I apologize in advance haha.

    I've got an 2003 dually I bought for a work truck and run fine for a while.

    I replaced the radiator and since for some reason everything went downhill in a hurry.

    Truck had what I think was a knock from the CP3 but I'm not sure.

    It progressively got harder to start, now barely starts at all. When it does bust off it runs for a few seconds and does. I've replaced the lift pump, added one to the tank, replaced the filter, and the FCA.

    Also bought two new batteries. Checked fuses couldn't find anything and I'm at a dead end.

    I think it's the CP3 but just trying to figure it out before I go to replace it.

    Any suggestions would be great!

    Thanks in advance.


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    WE WILL STAND! IGOTACUMMINS's Avatar

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    Re: Need Help! 2003 Hard Start/No Start

    Let's ask @Polaraco?

    "The grass is greener where you water it"


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    timshooter40's Avatar

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    Re: Need Help! 2003 Hard Start/No Start

    Have you put on a fuel pressure gauge on your CP3 pump and checked pressure readings?

    2016 Ram 2500 CCSB 4X4 ,Cat fuel filter delete with water seperator. Thuren suspension
    with Fox IFP shocks, thuren sway bar, rear track bar and front track bar, Warn 12k winch , custom winch mount, REVMAX trans pan,HD valve body and thermal bypas. Leer truck topper,Exotic head studs, Engine enhancements by the cummins whisper.

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    68muleteem's Avatar

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    Re: Need Help! 2003 Hard Start/No Start

    Being an electronic engine I would start by checking what it sees for fuel pressure.

    I have repaired several of these with a bad return circuit on an injector.

    You have to plug each line at the fuel rail one at a time to find this.

    If you can either it and it will stay running this is most likely the problem.

    It just will not build enough pressure to let it start.

    2011 Big Horn CCSB. 3.73 gears, 68RFE, 255/80/17 Cooper SSTMaxx, 4" flo pro out the back, Race Me Ultra from Doublerdiesel, Full delete on top

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  8. Top Of Page | #5

    Re: Need Help! 2003 Hard Start/No Start

    There was a rail pressure gauge on the truck but it quit working about a week before this started.

    I know its pushing enough fuel to the CP3.


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  10. Top Of Page | #6

    Re: Need Help! 2003 Hard Start/No Start

    68muleteam

    So you would either it to see if it stays running?

    That would most likely been it's an injector issue?

    The truck to me never seemed like it had an injector problem until it quit.


  11. Top Of Page | #7
    Old & Grumpy! Polaraco's Avatar

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    Re: Need Help! 2003 Hard Start/No Start

    Quote Originally Posted by Rider2767 View Post
    Hey guys, this is my first time posting so I apologize in advance haha.

    I've got an 2003 dually I bought for a work truck and run fine for a while.

    I replaced the radiator and since for some reason everything went downhill in a hurry.

    Truck had what I think was a knock from the CP3 but I'm not sure.

    It progressively got harder to start, now barely starts at all. When it does bust off it runs for a few seconds and does. I've replaced the lift pump, added one to the tank, replaced the filter, and the FCA.

    Also bought two new batteries. Checked fuses couldn't find anything and I'm at a dead end.

    I think it's the CP3 but just trying to figure it out before I go to replace it.

    Any suggestions would be great!

    Thanks in advance.
    You should have codes. Have you checked for them?

    Knocks in the CP3 are common. It's usually gear lash and not the pump.


    2003- 3500 RWD Automatic.
    S & B intake, BD Intercooler, Pusher Air Horn, MM3 Double R Tuning, Turbo Timer, electric Flex-a-lite fans, FASS 95,
    50 HP tips, upgrade to 351 turbo, 3.42 gears, Twin air compressors, air bags, Remote dual oil filters, Hellwig sway bar, Front Winch. Home made Fuel Heater, BD Exhaust brake with Torque Lock. Tons of TLC

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  13. Top Of Page | #8
    Old & Grumpy! Polaraco's Avatar

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    Re: Need Help! 2003 Hard Start/No Start

    Quote Originally Posted by Rider2767 View Post
    68muleteam

    So you would either it to see if it stays running?

    That would most likely been it's an injector issue?

    The truck to me never seemed like it had an injector problem until it quit.
    There was an issue with carbon buildup in the heads. Been a while since I've seen that.

    When it is running, is there any smoke?


    2003- 3500 RWD Automatic.
    S & B intake, BD Intercooler, Pusher Air Horn, MM3 Double R Tuning, Turbo Timer, electric Flex-a-lite fans, FASS 95,
    50 HP tips, upgrade to 351 turbo, 3.42 gears, Twin air compressors, air bags, Remote dual oil filters, Hellwig sway bar, Front Winch. Home made Fuel Heater, BD Exhaust brake with Torque Lock. Tons of TLC

  14. Top Of Page | #9

    Re: Need Help! 2003 Hard Start/No Start

    Quote Originally Posted by Polaraco View Post
    You should have codes. Have you checked for them?

    Knocks in the CP3 are common. It's usually gear lash and not the pump.
    I just bought a code reader today and am going to check it.


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  16. Top Of Page | #10

    Re: Need Help! 2003 Hard Start/No Start

    Quote Originally Posted by Polaraco View Post
    There was an issue with carbon buildup in the heads. Been a while since I've seen that.

    When it is running, is there any smoke?
    No smoke at all.

    Other than black on a couple tunes that I kept it off of.

    Am going to flash the ecm back to stock when it is running again.


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