QSC 8.3 CM554 - No Start hard to diagnostic

[J99]

Next chapter was next morning...it did not want to start again (only few seconds then dies) despite working the day before...code 456 at each attempt, and 276 too at some.

As I saw on Calterm that the fuel pressure at start of injection command was low (820 psi, compared to 4000 - 5000 the day before), I suspected some obstruction in the accumulator (before the fuel sensor which is the one shooting error 456). So I went ahead and opened the CAPS accumulator to check it and clean it.
Nothing special found in it except some dirt from old fuel but I cleaned all with ultrasonic + revived the key valves and contact surfaces, and reassembled it.

And it fired again this time, no error code, looks to work normal after a few stop and restarts ...let's see for how long. I hope this could help others.