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Thread: 2007.5 Cummins 6.7L Shutting Off For Split Second

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    Cody318's Avatar

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    2007.5 Cummins 6.7L Shutting Off For Split Second

    Under heavy acceleration or heavy load up, like trying to boost launch right before it breaks traction, it drops out as if almost defueling for a split second, then jumps back up, then does it all over again.

    Appreciate any help; hopefully, someone has info because I'm stumped LOL thank you.


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    Watch Dog! Corkey's Avatar

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    Re: 2007.5 Cummins 6.7L Shutting Off For Split Second

    Is there still a problem?

    Any changes with mods?

    Miles on CP3 pump & injectors?

    Dirty fuel filters?

    Have you verified the voltage of the rail sensor?

    The list can go on, but I will need a little more info.

    Two weeks have gone by, and you might already have this fixed by now.

    II 60HP STICKS, II 33% CP3, II S464 2ND GEN SWAP, FASS 165 TITANIUM SIGNATURE SERIES, AFE INTAKE HORN, S&B FILTER, 5" TURBO BACK, ALPHAREX HEAD LIGHTS, 38X13.5X20 RAZOR M/T, MOTO METAL RIMS, 6" LA LIFT KIT, COMPLET MM3 KIT, BUILT TRANSMISSION, 6 BOLT REDHEAD STEERING BOX

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    Cody318's Avatar

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    Re: 2007.5 Cummins 6.7L Shutting Off For Split Second

    Quote Originally Posted by corkey View Post
    Is there still a problem?

    Any changes with mods?

    Miles on CP3 pump & injectors?

    Dirty fuel filters?

    Have you verified the voltage of the rail sensor?

    The list can go on, but I will need a little more info.

    Two weeks have gone by, and you might already have this fixed by now.
    No changes in mods; well, besides, I put a new turbo on but stayed factory style with a Fleece Cheetah and no fluctuation in rail pressure; the desired is like 26000, and the actual will hold about 26500 and will spike to 29006 has new fuel filters; it pulls good and strong only time it does it is if I'm trying to boost launch holding break trying to build boost, but it's almost like it's just shutting all fuel off for a split second and refueling before I can build boost up it has me stumped.

    Still, as far as checking the rail sensor, I haven't checked it out; how would I go about doing that thank you for the help.

    Sent from my SM-N986U using Tapatalk


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    Watch Dog! Corkey's Avatar

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    Re: 2007.5 Cummins 6.7L Shutting Off For Split Second

    The rail pressure sensor is calibrated to output a signal between 0.5 V and 4.5 V with changing rail pressure across the range 0 bar to 1600 bar.

    This provides two opportunities for the ECM to undertake a signal plausibility check: any voltage above or below these values, for example, either at 0 V or 5 V, will indicate that the sensor has failed.

    Unplug the connector from the sensor and check the voltage from the sensor itself and from the pigtails.

    What could be happening as you hit the peak of pressure in the rail, its activating the sensor to open up and returning the fuel to the tank.

    The sensor of course is a bit of a pain.

    Remove the engine hook to gain room.

    Some say it's easier to remove injector lines, but I did not go that route just because I didn't a potential leak to worry about.

    If actual vs desired are very close I would assume the FCA is working properly.

    One step at a time though.

    I personally bought a plug off instead of shimming mine, do a little research for what direction you'd like to go

    Be careful unplugging the connector off the sensor, mine seemed impossible with pushing on the tab but eventually came free.

    II 60HP STICKS, II 33% CP3, II S464 2ND GEN SWAP, FASS 165 TITANIUM SIGNATURE SERIES, AFE INTAKE HORN, S&B FILTER, 5" TURBO BACK, ALPHAREX HEAD LIGHTS, 38X13.5X20 RAZOR M/T, MOTO METAL RIMS, 6" LA LIFT KIT, COMPLET MM3 KIT, BUILT TRANSMISSION, 6 BOLT REDHEAD STEERING BOX

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    Cody318's Avatar

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    Re: 2007.5 Cummins 6.7L Shutting Off For Split Second

    Quote Originally Posted by corkey View Post
    The rail pressure sensor is calibrated to output a signal between 0.5 V and 4.5 V with changing rail pressure across the range 0 bar to 1600 bar.

    This provides two opportunities for the ECM to undertake a signal plausibility check: any voltage above or below these values, for example, either at 0 V or 5 V, will indicate that the sensor has failed.

    Unplug the connector from the sensor and check the voltage from the sensor itself and the pigtails.

    What could be happening as you hit the peak of pressure in the rail?

    It activates the sensor to open up and return the fuel to the tank.

    The sensor, of course, is a bit of a pain.

    Remove the engine hook to gain room.

    Some say it's easier to remove injector lines, but I did not go that route because I didn't want a potential leak to worry about.

    If actual vs. desired are very close, I assume the FCA is working correctly.

    One step at a time, though.

    I bought a plug off instead of shimming mine, do a little research for what direction you'd like to go.

    Be careful unplugging the connector off the sensor, and mine seemed impossible with pushing on the tab but eventually came free.
    Ok, thank you.

    I'll check it to make sure it is working.

    I've never really been tech-savvy with sensors, but I think I can accomplish that task.

    LOL, I already put the plugin mine and can't see any leaking injector feed lines that I can see, and no clue on how tired the injectors are.

    I pulled my camper, it's about 17,000pounds with it a few days ago, about a 4hr trip with decent hills, and it did fantastically, no overheating or sluggish.

    Sent from my SM-N986U using Tapatalk


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  11. Top Of Page | #6
    Watch Dog! Corkey's Avatar

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    Re: 2007.5 Cummins 6.7L Shutting Off For Split Second

    If you leaked a line, you would notice the rig having a longer crank time starting the truck and a raw diesel smell.

    I'm just throwing out potential solutions that could narrow the issue down.

    Generally speaking, the sensors do go bad but not too often.

    Please keep us updated!

    II 60HP STICKS, II 33% CP3, II S464 2ND GEN SWAP, FASS 165 TITANIUM SIGNATURE SERIES, AFE INTAKE HORN, S&B FILTER, 5" TURBO BACK, ALPHAREX HEAD LIGHTS, 38X13.5X20 RAZOR M/T, MOTO METAL RIMS, 6" LA LIFT KIT, COMPLET MM3 KIT, BUILT TRANSMISSION, 6 BOLT REDHEAD STEERING BOX

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