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Thread: 2018 20k miles draining rail psi

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    2018 20k miles draining rail psi

    Like the title states I’m having an issue not being able to even get close to desired pressure even on my tow tune. Truck has never had any issues besides me putting s built trans in it with triple disk converter. I even installed a industrial bag of parts kit and still max pressure is about 25k rail pressure at WOT. In my extreme tune and max tune it gets up to 25k and will bounce around 23-24 and will surge like I’m letting off. Just was wondering if anyone else was having an issue. Oh and I have even tried a rail plug to see if the relief was popping open.


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    Daily Grinding! RamIt's Avatar

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    Re: 2018 20k miles draining rail psi

    I might be wrong but I thought the CP3 maxed out at like 26k?

    2021 3500 Mega HO DRW

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    Western's Avatar

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    Re: 2018 20k miles draining rail psi

    Quote Originally Posted by RamIt View Post
    I might be wrong but I thought the CP3 maxed out at like 26k?
    I have seen mine hit 28k one time but I've seen 27k alot

    Sent from my SAMSUNG-SM-G935A using Tapatalk


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    Kyle Workman's Avatar

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    Re: 2018 20k miles draining rail psi

    Quote Originally Posted by Western View Post
    I have seen mine hit 28k one time but I've seen 27k alot

    Sent from my SAMSUNG-SM-G935A using Tapatalk
    Mine will also easily reach 27-28k. Especially if he's getting surging i'd say there's an issue.


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    Re: 2018 20k miles draining rail psi

    I just don’t know what it could be, I’m gonna do some testing today and hook up a fuel pressure gauge, and unhook the FCA for a small second to see what it pegs at. It doesn’t smoke, cranks right up, and runs great other than the lower than desired pressure.


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    Western's Avatar

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    Re: 2018 20k miles draining rail psi

    But here is something else to keep in mind guys; tuning also has to do with your rail pressure

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    Western's Avatar

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    Re: 2018 20k miles draining rail psi

    Quote Originally Posted by Casey Ross View Post
    I just don’t know what it could be, I’m gonna do some testing today and hook up a fuel pressure gauge, and unhook the FCA for a small second to see what it pegs at. It doesn’t smoke, cranks right up, and runs great other than the lower than desired pressure.
    What is the highest rail pressure you see? Also who has tuned your truck?

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    Permanent Vacation KeepEmRollin14's Avatar

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    Re: 2018 20k miles draining rail psi

    Id really like to know what tune setting your on, who tuned the truck and keep in mind that duration can effect your rail pressure as well on big tunes because of the injector staying open longer. Reason why I ask what the duration is, but one would think that if it is tuned you wouldn’t have an issue with rail pressure or anything within the tune.


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  13. Top Of Page | #9
    Permanent Vacation KeepEmRollin14's Avatar

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    Re: 2018 20k miles draining rail psi

    Excuse me for not reading the post correctly. I see your running extreme tune, what other mods do you have to support fueling? Sounds to me like it might be an issue with fuel supply and the demands your asking of the system with an extreme tune. I’d ask if you have an upgraded pump or lift pump. On extreme tune your probably asking for alot of duration and not able to hold rail pressure due to the rail draining down due to the length of open time on the injector. Best guess but if you could data log it and look at it you might be able to have some better info. Does it run like this on any other tune setting. Max pressure for your stock CP3 should be around 26000.


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    Daily Grinding! RamIt's Avatar

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    Re: 2018 20k miles draining rail psi

    Quote Originally Posted by Casey Ross View Post
    I just don’t know what it could be, I’m gonna do some testing today and hook up a fuel pressure gauge, and unhook the FCA for a small second to see what it pegs at. It doesn’t smoke, cranks right up, and runs great other than the lower than desired pressure.
    Can you clarify what is desired and why? Im not understanding what the issue here is. CP3 maxes around 26k and you sound like you're within range. My truck on a 120hp tune would have minor fluctuation at WOT and it was never an issue.


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