Same issue here bled at injector sites and does not seem to be getting fuel to rail in proper amounts, pulled CP3 and getting another new bosh reman, Oh Ya ... 03 3500 5.9, air dog, airade, new feeder tubes, 2 new batteries, new thermal electric fan clutch, but before pulling other remaned CP3 was throwing codes:
P2146, Fuel injection group 1 supply voltage circuit
P2149, Fuel injection group 2 supply voltage circuit
P 0480. cooling fan 1 control circuit open low speed fan relay
P0251, injection pump fuel valve feed back
Batteries unhooked cleared all those codes and is throwing nothing now. I'll put the new, new CP3 in and see what happen then, pump guy said it could be electric signals to the CP3 that is bad but no way to check with pump out any ideas? My knuckles are sore and I still love my truck!
Real interested to see where this leads to. Thanks

 

Found out CP3 I bought and installed and removed was used in another truck, gota love that it was supposed to have been a new reman from bosh. Had to get a friend who happens to be a mechanic involve to find out the truth. Shop is still saying it should be good but will replace it anyway???? So I will install the new one when I get it, and see what happens.