Fuel Pressure Number?

[Marc-11]

Hey all, sorry if this has been posted before but the search keeps giving me an "oops - server error" message. I'm trying to figure out if I have a lift pump issue in my 2015 Ram where the truck won't start or started for a second but never gets enough RPM and the starter keeps trying to start it. The truck sounds like it's starved of fuel. I've pulled off the fuel line in front of the C4 and I am getting fuel. I've pulled the metering valve or sensor (not sure) from the C4 and the filter is clean and the fuel is clean (no metal). I have a XTOOL D8 scan tool and when I set the ignition to RUN and view live data I get a line that says FUEL RAIL PRESSURE TARGET 269.95 BAR and a second line below it that says FUEL RAIL PRESSURE MEASURED (SENSOR) 7.06 BAR. That's a pretty big delta . When I put the ignition in the RUN position the pump is timing out trying to pressurize the system. My gut (and this limited data) leads me to believe it's the lift pump but I'm not sure those two values above are supposed to match or be closer together when the truck is not running put the line is primed. The truck started to shrug on me on the road and then picked back up only to start shrugging again 30 seconds later then my electronic accelerator quit working at a four way stop because the rpm at idle dropped supper low and the engine was misfiring. Any ideas on the fuel pressure measurement?

 

[BoostN]

I don't have any info for your issue, but I've fixed the search issue. Thanks for bringing it up!

 

[Fuelie]

Does the measured stay at 7 bar when it is first trying to start?
Tom

 

[Marc-11]

Hi Tom, no, it appears to track track correct. I've attached a photo (that I for some reason cant rotate) of target vs actual and also duty cycle on the Fuel Pressure Regulator on the common rail as well. It's not the FCA on the CP4 (replaced), it's not the FPS (replaced). I'm starting to think its not a fuel problem at all. If I let the truck sit over night and I turn to key to run and let the fuel pump run for 10 seconds or so I press start and the truck cranks short, starts, stalls in 3 seconds. If I move teh key back to run and let the pump prime agian and then try and start it's like the the starter is chasing the engine, it cranks and stumbles but never staqrts and the starter keeps trying. I have to press the ignition button again to get it to stop. The few times it rumbles to life teh accelerator peddle is dead feeling (cant rev the engine) and it runs super rough for 5 - 10 seconds before rpms drop to a stall. I was thinking about pulling teh starter and tring to put a camera in to look at the tone ring.