Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
All, seeking some help with a diag im having some issues with. Working on a 2012 Ram 5500 with a 6.7L Cummins in it. Customer reached out stated the unit was driving fine and then randomly started stumbling and eventually stalled out, started up one time after and then died right out. Hasn’t started since. Customer changed fuel filter themselves with no change. Customer mentioned that the fuel cap had been missing for some time and inspection of the fuel bowl displayed a lot of gunk and debris in the bowl. Truck has no codes, certain response tests I’ve performed have set no codes either, for example I can’t get any fuel injector circuit codes to set period. I’ve checked rail pressure with the FCA disconnected to default it to max and the rail pressure reads about 18,500psi while cranking. Ive removed the EGR cross over tube in case of restriction, no change. I’ve tested and replaced the PRV in the rail, no change. Eliminated each injector electrically one by one with no change. Inspected turbo to see if VGT was stuck closed, was not. Inspected the psi to the fuel bowl from lift pump and it was good, fills the bowl in under 10 seconds. I did not perform a return test because I was under the impression that if it was leaking off that much I would see that in my rail pressure results. I’ve checked every fuse and inspected wiring below the TIPM. I’ve checked cam and crank signals as well as the crank tone wheel. Some of these steps I’ve written out of order simply because this has been a long diag. I’ve narrowed my thoughts down to either the injectors aren’t being commanded, low compression, or the injectors themself failed due to the amount of contamination. I’m in the process of hooking up my scope to the injectors and for a relative compression test, however I’ve never used this scope or any for that matter so the waveform analysis is new to me. The few questions I have are 1. Could I be showing a false rail pressure? Like is my scan tool saying I have 18k but in reality it’s bleeding off instantly and never firing my injectors? 2. The PCM has modified/programmed, is the circuit response for the injector circuit an indication of internal failure? I haven’t yet checked powers and grounds to the PCM only because I’d like to verify a power loss to the injectors prior to chasing wires. Any thoughts, tips or advice would be greatly appreciated. Apologize if I forgot any of the steps I’ve taken and the fact that they are out of order. Thank you.
Topic Author
