Optimum Rail Pressure
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Pull the return line going to the tank and stick it in a container that has graduated measurements on it. Start the truck and let it idle. You measure how much fuel you have after one minute and it will tell you if the FPRV is functioning properly. I'll have to look up the specs on the return volume thought. Cant remember off the top of my head.
#7
There are a few things that happen in regards to rail pressure. The first is the supply to the CP3 which it looks like you have covered. The second is the command from the ECM to the FCA for rail pressure. The FCA then lets the CP3 make whatever pressure is commanded. What is commanded is compared with what the actual pressure is at the rail pressure sensor. If the two are withing paramters then your on your way. If not, the ECM will ikely shut the CP3 down via the FCA. The things that can make this haywire are the obvious, the CP3 has mechanically failed, injector(s) stuck open, FCA is bad, relief valve is bad or the ECM is bad.
#8
i switched out the fca with another truck and it didnt fix it. the relief valve has been changed also. im hoping i can get another cp3.."under warranty" and that fixes the problem. the truck runs until it gets warm and then it shuts off and wont start for a few minutes. as the truck was warming, the quadzilla rail guage was dropping lower and lower until it hit 0 and then the truck died.