6.5 IP Pump issue

I have a 6.5 Suburban 279K has a good wrench engine now, no idea when it was installed. runs poorly. A non qualifed show installed an injector pump, did not have the OBD1 scanner to set DTC. This was a year ago just borrowed a GMTD scanner, it has 3 codes 18 pump cam reference error, 35 injector pulse width error, and 54 PCM fuel circuit error. DTC is now is -0.65 Desired timing is10.9, Actual is 14. if you run it 5 minutes on a hot day and rev it up it will run good, with check engine light comes on.

Any ideas?? I won't go back to the shop that installed the pump, he can't fix 6.5's

Welcome to the board!

DTC-18, appears when there is a problem reading the optical encoder sensor data. This sensor is located in the very top of the pump.
DTC-34, The PCM is unable to control the injection timing using the timer stepper motor and transverse mounted advance piston. The physical position of the pump has to be within a window of acceptable timing for the PCM to manage the timing.
DTC-54, Like you included, this is due to a PCM sensing a fuel circuit error. PMD, wiring, no calibration resistor installed... lots to check, and the first two codes could be causing the last.

First step... Have a knowledgeable 6.5 tech perform a TDC-Offset Learn procedure using a genuine Tech I or II scan tool that has the current GM 6.5L diesel package installed. Gotta do this. A Tech II scan tool, made for OBD-II, comes with an adapter that allows it to be used on OBD-I systems. The process could very likely solve your code problem, or help to provide more insight into possible causes. Having a known-good spare PMD is essential for any electronic 6.5 owner. Get the newest gray colored driver module produced by Stanadyne along with a #5 resistor.

Jim