Rail pressure loss

sjsuliman

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Hey guys, new here. Anyway, I’m having trouble isolating an issue with my 6.4. The truck started to have a random loss of rail pressure. I’d just be cruising along and it would drop from normal rail pressure to as low as 1.8k psi. I’d let off or get on it more and it would go back to normal. It only does it cruising, never heavy throttle. I checked low pressure psi from my Fass and it was good also at 10 psi. I also changed the fuel filters and nothing changed. I found metal in the fuel bowl so I changed and cleaned the whole fuel system, including HPFP, injectors, Fass, fuel bowl ******, new lines, cleaned fuel tank, and all that. Also put in a new FRP sensor and UVC harness. I used Alliant for the HPFP and Ford for the injectors. Truck runs amazing now, even better than ever and it still has a loss of rail pressure. Truck has good low fuel pressure, fuel is clean, it’s not throwing any codes, and I’m really at a loss here guys. I heard something about resetting the adaptive fuel tables, but would that loss of rail pressure be in that memory? I know I need to do it but I haven’t been around a scanner. Thank you for any help I can get.
 

sootie

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what tuning are you running?
Yes clear adaptive fuel tables
i have seen a bad pcm do this as well.
 

sjsuliman

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I’m running an H&S mini maxx with Byall tunes. They always ran good. I’ll clear the fuel tables as soon as I can get around to a scanner. How would I be able to test the PCM?
 

sjsuliman

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I’ve cleared the adaptive fuel tables and injectors and it’s still doing the same thing. I just can’t narrow this problem down. I even looked to see if I had a dead pedal but that’s not the case either. Does anyone have any other ideas?
 

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