CP3 Failure

[Ed'sTransmissionService]

Just completed diag on 03 DR 3500 nostart, using TSB 14-003-06 RevA, as directed by Chrysler. Truck has 144K, no mods at all. In tank lift pump recently installed(by me). Truck has always had long crank time, scan tool shows actual fuel pressure slow to build to set point. Lift pump fuel flow exceeds minimum specs After diag, there is less than 100PSI during cranking. Unplugged FCA, no change(should have maxxed PSI). Performed hi pressure fuel flow test as directed by TSB, fuel flow was minimal. Result? failed CP3. No evidence of contaminants. My question is this: why do CP3 pumps fail? I've r&r untold # of vp44 pumps, and some common rail injectors, but no cp3 pumps. Just curious,,, Ed. Chrysler(my employer) offers no explanation.

[Wild and Free]

It is a really simple piston pump, As do all pumps they are all prone to failure at some point. They are suseptable to moisture and contamination and lack of lube "Lift pump failure" much like any other type of pump. The early cr's had a bit higher failure rate most likely due to coming with the 10 micron fuel filter they "Chrysler" have since changed "Recommend" to 7 micron fuel filters. I have seen plugs blow out of cp3 pumps already.

[Mopar1973Man]

Most are moving over to like a AirDog 100/150 pump with a 2 micron filter to protect the fuel system but also the enhanced fuel volume helps with keeping it lubed up. But also looking at Bosch requirements on fuel lubricity is <400 HFRR... Most today fuel is averaged out at ~520 HFRR which is too dry...

[dorkweed]

They're not difficult to change out; but, they are a bit of a PITA because of where they are located. Don't drop the CP3 nut or washer into the front cover or you'll have a much bigger project on your hands!!!!

[Ed'sTransmissionService]

Installed reman pump. Truck now starts and runs, but am experiencing extremely long crank times, upwards 10 to 20 seconds when cold. reverified lift pump flow, almost 900 ml in 20 seconds, now flow 120ml fuel from hi pressure line, so new pump is flowing fuel. Question: When testing the pressure limiting valve with Miller tool 9013, no fuel flow from tool is good. However, when activating fuel pressure override with scan tool, slight fuel is observed. Service info says to replace valve if fuel is observed from either test. This small. simple valve lists for close to $500. I retorqued all 6 HPC connectors in head, several were under torqued. What am I missing? No DTC, ECM calibration is at most recent level. Truck has no mods. I await your wisdom! Ed

[Mopar1973Man]

I would say its on the supply line to the lift pump has a air leak. Being its all suction line from the lift pump back to the tank it really easy to over look a air leak because it NEVER leaks outward... So to verify this pressurize the fuel tank with about 1-2 PSI most and look for wet spots in the fuel lines...

[Wild and Free]

That is classic bad injector related issues with 03 models. What are the rail pressures while cranking? They tend to stick and return fuel it needs in the range of around 6kpsi to start IIRC. They will run fine ect but the injectors are about dead. other than that retorque the connecting nuts to 40 ft lbs to make sure there are no leaks.

[dorkweed]

That is classic bad injector related issues with 03 models. What are the rail pressures while cranking? They tend to stick and return fuel it needs in the range of around 6kpsi to start IIRC. They will run fine ect but the injectors are about dead. other than that retorque the connecting nuts to 40 ft lbs to make sure there are no leaks.

:agree::agree::agree: There have been a lot of '03's on the various forums for about the past year with the same symptoms as yours. In the end, after replacing the cheap parts first, it winds up truly being the injectors. They just wear out. Think about have many times that solenoid has to fire with the multiple injection events. Some of the new injectors have stainless bodies and lighter weight pintles and harder seats so they "theoretically" last longer!!!

[zshaw]

Time for injectors. I would also install a FASS or Airdog pump with a 2 micron filter and use Standyne or Howes lubricity additive.

[Mopar1973Man]

Time for injectors. I would also install a FASS or Airdog pump with a 2 micron filter and use Standyne or Howes lubricity additive.

:agree: You could even use 2 cycle oil at 200:1 ratio to prtoect it better...