N13 high fuel pressure ongoing issues

Heavyd, i know this is an old post but having same issues. Its a 2017 Prostar with N13 engine. Replaced fuel pump in august, 7 months ago. Replaced fuel rail, sensor, and pressure release valve last week. Truck ran great until we put a load on it. Then get the 3055 fmi 0 code and derates to 45 mph. Ive checked all the fuel lines, installed a new return line. You think its the pump or should i look somewhere else. Once it derates you can pull over, let it idle a few mins and do a key reset and itll run good for about 10 mins then all over again it messes up.

 

You need to use Navistar Engine diagnostic to see what is going on. Record a road test under full load. When fuel pressure is nearing or exceeding 33000 psi, there are few things to look at. If FPCV (fuel pressure control valve) % is less than 30%, the fuel pump is over worked. This could be caused from aerated fuel, restricted fuel inlet. Look at regular fuel delivery pressure. Normal is 60-120 psi. If the pressure is lower (less than 70 psi) at higher RPM, you need to test for restricted inlet. If the pressure is bouncing all over, check for aerated fuel. If FPCV % is higher than 30% with 33000 psi, check for aerated fuel, or restricted fuel return. To check for aerated fuel, the clear test line is installed at the right, lower most fuel line at the high pressure pump.

 

Changed return line out. Still getting codes 5571 fmi 14 and 3055 fmi 0. Fuel pressure was 124 psi and railer pressure was 34808 when faults accurred during road test

 

Do you know what the FPCV% was during that? You need to measure return fuel pressure. A test line is plugged in the fuel line at the very front fuel line connector at the fuel pump to measure return pressure there. Max allowable is 13 psi. Your fuel delivery pressure is a tad out of spec on the high side.