LBZ won't hold rail pressure at idle

[Chevyhead3]

The part of this I don't understand, is why is the desired fuel rail pressure reading same as the actual, when the FPR is unplugged? I get that it is possible for the CP3 to only be putting out 12-13k psi. max out, if it was bad or excessive return from injectors or a leak? But shouldn't desired read max 28-29k? As said before with it plugged in I can raise desired with scan tool, but no change in actual. I did send out the ECM out for a bench tune, since the EGR was deleted,

 

[Chevyhead3]

I did pull the both connectors on engine side, and ECM connectors back off, cleaned and looked at the pins very closely to make sure that wasn't an issue. Since there is a TSB on that.

 

[Chevyhead3]

I obviously get codes P0087, P0088, P0090, when FPR is unplugged, but no codes with FPR plugged in, idling, but when I apply throttle I get low rail pressure code p0087

 

[Chevyhead3]

I was unable to log any live data while driving with FPR plugged in, because it doesn't run off idle with FPR plugged in, Won't throttle up Truck has 163k mi. on it.

 

[juddski88]

Yeah you've got some wiring issues. Load test

 

[Chevyhead3]

juddski88, You wouldn't by chance have a procedure/schematic for this? Thanks

 

[juddski88]

juddski88, You wouldn't by chance have a procedure/schematic for this? Thanks

You can get schematics and pinouts from alldata or gmupfitter. Procedure is buy a loadpro and have a good multimeter, disconnect the circuits you need to test at both ends, hook one end to 12v, put the loadpro in series at the other end to ground. Press the button on the loadpro and watch for voltage drop.