Cp3 problems need advise

r-rated diesel

r-rated diesel

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Oct 6, 2011
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I installed my new 250% exergy injectors and my two stock pumps aren't keeping rail pressure up. At wot pressure falls all the way to 6k. I was told to check the cp3s by unplugging the fca's one at a time and see how it acts because it shouldn't be falling that bad. When I unplugged the top dmax pump it smacked 26k. So I plugged it back up and unplugged the bottom one and the truck ran rough for a min then died. Does this mean the bottom pump is bad or fca is bad?? Any help or advice would help a lot. Thanks!
 
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Without looking at live data, I would say yes bad FCA. Got an extra? Or maybe swap them around to find out what you have.
 
Thinking outside of the box....is it possible that the lift pump isn't keeping up?
 
The Dmax and dodge FCA are different so switching them around may not be the best diagnosis. If you still have your single pump belt you can put it on and that will help you see if it is the stock bottom pump that is failing. More than likely tho, its just the dodge fca.
 
BanjoDiesel said:
The Dmax and dodge FCA are different so switching them around may not be the best diagnosis. If you still have your single pump belt you can put it on and that will help you see if it is the stock bottom pump that is failing. More than likely tho, its just the dodge fca.
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I replaced the dmax fca with a cummins one last year. I was told to do that by someone lol. I'm gonna try just running the bottom pump by itself and see what happens.
 
Yeah flip the belt off and run the bottom pump/factory fca driver and see where your at.
 
Just for learning, when you unplug the FCA on these trucks, it will command full rail correct?
 
That's what I was told as well. When I unplugged the top pump rail pressure was wide open. Not so much when I unplugged the bottom one haha.
 
i would think a bad lift pump would kill the "good" pump after a few seconds anyways.

FCA is a cheap and easy fix.

what are you using to control the 2 FCA's?
 
SixOhh said:
i would think a bad lift pump would kill the "good" pump after a few seconds anyways.

FCA is a cheap and easy fix.

what are you using to control the 2 FCA's?
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I'm not sure. Dmax's don't run lift pumps from the factory. Isn't the pump slightly different to the Cummins ones?
 
I'm figured it out it was a bad fca on my bottom pump. I still have bad issues. It holds good rail pressure but I took it to the track last night and every time it shifted it fell on it's face and defueled. And the last pass I made my converter won't unlock now.
 
Full time lockup= you can show kids how to oralz the coalz like a boss! Lol. Jk, hope you get it figured out man.
 
r-rated diesel said:
I'm figured it out it was a bad fca on my bottom pump. I still have bad issues. It holds good rail pressure but I took it to the track last night and every time it shifted it fell on it's face and defueled. And the last pass I made my converter won't unlock now.
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Wish I had known. Would have liked to watch
 
biggy238 said:
Wish I had known. Would have liked to watch
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Trust me you didn't miss anything haha. It spun like crazy fell on it's face after every shift and I couldn't even get on top of the turbos. Still ran a 11.3 haha. It felt way slower than that. Not to mention the Trans issue now:nail:
I felt like burning it when I got home lol
 
r-rated diesel said:
I'm figured it out it was a bad fca on my bottom pump. I still have bad issues. It holds good rail pressure but I took it to the track last night and every time it shifted it fell on it's face and defueled. And the last pass I made my converter won't unlock now.
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Please call Me. 763-228-7121 Todd.
 
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