hello ford techs., gm tech here having problems with powerstroke motor. got to be something simple, intermittent problem of no start, will turn over great. change out cam sensor(had a code), no code after changing out sensor still no start. new batteries, all fuses ok, have good fuel pressure, this truck belongs to the local Rescue Unit and we are trying to figure out without spending a lot of money. Someone metioned a (fuel-servo)???? not sure where it is or if it exsist. If truck sits for a while like a week then this happens. oil level is good but not sure when last changed. looks dirty. could that have something to do with it????
ANY INFO WILL HELP.
Thanks
John

 

The easiest, best way to diag this is to read some data from the data stream. Check RPM, IPR %, VPWR, and ICP (use either press or volts). The rpm will obviously be cranking speed. IPR sould read about 14%, VPWR should be at least 9.5 volts, and ICP should very easily go over 500 psi. If there's no RPM, that means the CMP sensor or its circut has a problem. The vpwr is critical in these, as they always seem to come in dead, and I have to charge/replace the batteries just to diag them. The IPR is the thing that controls the H.P. oil pressure, and the ICP reads that (It's a closed loop system). Look at the ICP; it should have no problem at all going well over 500 psi. Also, if all is good, then check the glow plug controller (you can always use the old screwdriver trick if burnt out), and the glow plugs for opens. I didn't say much about the fuel pressure, but you said it was OK (these enginges will even run with negative fuel pressure, but not well; If fuel pressure is not exsistant at cranking, sometimes they won't start). Good luck and let me know.

 

need to get another scanner with more info on it. the vpwr was good, could not find title for IPR or ICP. was using a little mac scanner, is there another title it might be under?? the CMP was showing rpm but only about 100-150 rpms? seemed like it was spinning over faster than that???but I did have a signal.
what does ICP & IPR stand for? looked at scanner and didn't see anything with that initials or any readings like that. Is it ok to spray ether to see if it will start? Heard that isn't good to do that on a diesel.

thanks
john

 

ICP stands for Injection Control Pressure, and IPR,, Injection Pressure Regulator. 7.3 needs to crank at a minimum of 100 RPM or it wont fire.. Was there a 'fuel pulse width' indicated when you were cranking the engine? As noted before, you need to see the PID values for IPR, IPC, RPM and pulse width. The IPR and IPC values will help you diagnose if a possible HP oil system bleed, bad regulator, pump ect, and will give you the base pressure reading needed for the injectors (500 minimum)

Adding 'any' fluid as a starting aid into the intake with the glow system 'active' can be dangerous, or at the least could flame out the intake.