i have a c4500 topkick and have a p1093 code. it is a intermitant problem the truck will run 700-1000 miles before the code is set, the injection pump has been replaced, fuel rail pressure sensor, fuel rail regulator have also been replaced. i could use some new ideas please help.

sounds like injectors..it needs to have the pressure ramped with a tech2 or similar device...and return rates measured

Use the search function for P1093. The CP3 is the most likley reason, but not the only one. There are several things that could cause it. Check for air getting in the system, but search and read.

this is out of my 04 service manuals, since you did not give any info about your truck,except 4500. the causes are, excessive fuel return to the tank, a fuel injection pump failure, a fuel pressure regulator failure, if you have to prime the system, it could be a fuel supply line air leak, sticking fuel pressure regulator and it is also possible for a short circuit or worn through wire or bad connection.
The conditions for setting this DTC, the difference between commanded fuel pressure and actual fuel pressure is more than 20MPa. The FPR regulator fuel flow is more than 15,000mm3 at 800RPM or more than 38,000mm3 at 2000RPM. books are wonderful charlie

sounds like injectors..it needs to have the pressure ramped with a tech2 or similar device...and return rates measured
thanks for the help i will try that