been fighting code p0148. a couple of people suggested changing this valve. been told it is on the back of the head! i have spent 30 minutes and cant find it. anybody know where it is?? does the valve cover have to come off???

 

pulled a diagram off of cummins quick serve- boy this looks hard to get at!

 

Anything is possible, but that particular item is not likely. Run a injector return flow test for a mnimum and maximum flow. That is a better indicator if the orfice is faulty. A plugged return flow will blow the tops off the injectors. A partial plug would show as low return rates.

That code is a generic catchall for a LOT of issues. More than likely it is a fuel delivery discrpency between the rail and the IP. This could be bad injector(s), bad FCA or COV, bad rail pressure sensors, bad CP-3, low LP fuel delivery, or even a weak rail PR valve.

Have you run test with a scanner to determine demanded and actual rail pressure under multiple driving conditions?

Have you changed the FCA, COV, RP sensor or PR valve? The FCA and COV are relatively cheap to swap. The others a bit more expensive.

Checked LP delivery pressures?