Commanded fuel pressure stuck

[tree98]

(11-10-2023 )windowrattler Wrote:  I know the engine terminating resistor by the aft treat might not be hooked up but I don't think a datalink problem would present itself this way.

The fuel pump actuator is on J1939. So if your missing a terminating resistor the data is getting clobbered, that could explain why the commanded is sticking on certain pressures, maybe theres default pressure settings in the program that the ECM uses if it isn't getting the information it needs to calculate commanded rail pressure correctly (just a guess) ??

This could also explain why it won't throw CEL with the stock program, when all the components are operating on the J1939 the signal might just get clobbered and not make it where it needs to go. The modded cal eliminates all the traffic and the signal makes it through.

Those are just the first things that come to my mind after reading what you posted. If I were you I would take the 10 minutes and replace the resistor, rule it out atleast so you can move on instead of guessing and wondering.