low rail pressure twin cp3 issues

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wag06cummins

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Mar 27, 2011
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hi been messing around with my truck off and on for a few weeks trying to trace this problem, here is the prob. at idle rail pressure is fine as soon as i touch the pedel rail pressure drops to 3-4k but will build with rpm very slowly truck just smoke heavy until pressue builds i have a hell man sump airdog 150 truck ran fine this came out of the blue also ats twin cp3 kit,180 hp injectors, tc relief valve i put my rail plug in just to see if it would help did nothing, should i look at feed tubes, fcas ? top pump is the dmax pump, any input would be helpful if anyone has ran into similar issue.thanks :bang
 
I would start with FCAs, maybe even the RP sensor...Also what r u using for a guage to monitor RP?
 
I have also seen a truck where the rail pressure gauge was causing issues with the pressure.
 
Unplug the gauge and find someone local to log it with efilive. You dont need to license the controller to scan/log them
 
And......What mA and duty cycle was the ecm commanding at wot? Would be nice to get a log posted up with efi. Sounds like the fca is sticking. Unplug each one at a time and see what rail pressure does. If their bad or sticking it won't make max rail pressure.
 
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was a basic scanner only read rail pressure, but i did umplug both fcas and it spiked for each one could be sticking ? orginal stock pump only has 34k on it and dmax top pump has 2k but i guess they could still stick.
 
If it went to max, 24k+ each pump then the fca are most likely fine. The leaves rail pressure sensor, cp3 controller issues, wiring issues or ecm issues. Thats where it would be nice to log mA and duty cycle.
 
ComnRailPwr said:
If it went to max, 24k+ each pump then the fca are most likely fine. The leaves rail pressure sensor, cp3 controller issues, wiring issues or ecm issues. Thats where it would be nice to log mA and duty cycle.
Click to expand...

yes def need to see whats really going on not trying to throw parts at it lol.
 
around 15 psi, narrowed it down to cp3 controllor i retorqed feed tubes number six was a little loose so hopfully thats it, waiting on new rail sensor to put it all together.
 
I've had better luck running a ATS controller than the ppe one.

ATS, seems to react faster to demand
 
ive also had feed tube issues. if they aint lined up just right low rail pressure is common. id suggest getting new ones after 3-4 times of installing.
 
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