Guys, a CP3 is just like a VP44. It need excess fuel for lubrication and cooling. If your lift pump fails or is inadequate at WOT, it will damage the CP3 over time.

An engine with a damaged CP3 can have any number of symptoms, including:

- knock at idle (one of the CP3 plunger/barrels is scored)
- blowing injectors (bad fuel delivery to injectors at idle causes poor spray pattern on injectors, takes out nozzle.)
- hard start when hot (multiple plungers/barrels scored or worn)
- lack of power (CP3 not delivering enough fuel at high pressure)
- smoke at idle (one of the CP3 plungers/barrels is scored)
- leaking CP3. (Internal clearances allowing HP fuel where it shouldn't be or seal burnt due to lack of lubrication. Could also be a blocked return line.)
- poor fuel economy. (Low rail pressure under load. ECM compensates with longer duration.)

An engine that won't start when cold usually has a bad grid heater (air too cold to light fuel) or a bad lift pump (CP3 not getting fuel).

Bad injectors might also be the culprit, either bad nozzles or leaking control valve. The later is easy to check by cracking the return line on the back of the head and watching the fuel return flow as the engine is cranking. There shouldn't be much. If the nozzles are shot it will smoke while cranking but not fire.

No smoke while cranking means no pressure in the fuel rail which means CP3 is shot or lift pump isn't getting fuel to the CP3. Or both.

My 3rd gen starts fine by itself *with no grid heater* even at temps below freezing. I think down to 20F, I didn't watch that closely. About 5 seconds of cranking and it fires. A 3rd gen with a working grid heater should start by itself at -20F.

I've run a non stock (ie non Dodge) lift system since new. I wrote a post on it.

Easy way to diagnose all this is to watch the fuel rail pressure, maybe on an oscilloscope. Scan tool would work too. An oscilloscope would find a bad plunger and barrel if just one is shot.

It pains me to see the problems you guys have with your engines. I'm sure it is all due to the lift pump issue and damaged CP3s.

See the "Lift Pump Died" post for a harsh honest discussion.

Lift pumps don't have to be an issue. The lift pump in the Ford diesel trucks supplies 50-60PSI and they rarely fail. Ironically it is made by Bosch.

Sorry if I hurt anyone's feelings. Merry Christmas.

 

what exactly is a CP3 fuel bypass and a Walbro 392 pump and where do you recommend purchasing these parts.

I am fairly new to this forum but I am shocked by all the problems that people are having with the Cummins engines.............

I have owned an '89 CTD till 210K No Repairs
'93 CTD til 180K No Repairs
'92 CTD til 215K No Repairs
'96 CTD til 257K Replaced water pump and head gasket.
Head gasket was my fault, pumped turned up too much, too heavy of a load, going too fast, no EGT guage, but anyway
'02 CTD til 140K No repairs

I change the oil every 7,000 and on the '02 I changed the fuel filter with every oil change and on the older CTF with the spin on fuel filter I changed them every 14K. I run a quart of tranny fluid through them about once per month. Thats it, drive the pi$$ out od them.

I only have 10K miles on this '05 so I am curious to see if I have some of these problems. I posted a thread wanting you to reply about the pump because I do have it on my mind to go ahead and repalce the one on this '05 if I can do it without having to spend a fortune............thanks

 

You said in another thread we should replace the factory lift pump with a better one. What would a better option be and what do they cost?

Also which one of the pumps actually makes the pressure that supplies the injectors, the cp3?

How does running a box such as an Edge with juice effect all this? Will a box accelerate the failure or no effect at all? I'm really glad I never put one on now because my dealer isn't box friendly.

Why does the cold weather make the failures start appearing, thicker fuel?

Does working the truck bring the failure out sooner because it's working harder?

Are the pumps the same on the 04.5 and up as they are on the 03-04?

Hopefully this thread will develope and we all can learn more about our trucks, Thanks, LCH

 

"what exactly is a CP3 fuel bypass and a Walbro 392 pump and where do you recommend purchasing these parts."

I wrote a post on it. Search my posts and you should find it.

"I am fairly new to this forum but I am shocked by all the problems that people are having with the Cummins engines............."

I think the 3rd gens are outstanding engines. I think most of the problems people are seeing are CP3 related and that is being caused by lift pump issues. Simple to fix.

 

"You said in another thread we should replace the factory lift pump with a better one. What would a better option be and what do they cost?"

I wrote a post on this a while back. Search my threads and you should find it. A Walbro 392 is about $150.

"Also which one of the pumps actually makes the pressure that supplies the injectors, the cp3?"

Yep. It mounts to the front drive on the drivers side of the engine. Its the one with fuel lines going to it.

"How does running a box such as an Edge with juice effect all this? Will a box accelerate the failure or no effect at all? I'm really glad I never put one on now because my dealer isn't box friendly."

Boxes cause more fuel to be consumed at higher pressures. More chance the CP3 will starve and it works it harder = more wear if it does starve.

"Why does the cold weather make the failures start appearing, thicker fuel?"

Lift pump can't push fuel through the filter, meaning CP3 starves. Or lift pump fails to operate at all.

"Does working the truck bring the failure out sooner because it's working harder?"

Dunno. Probably.

"Are the pumps the same on the 04.5 and up as they are on the 03-04?"

I don't own a Dodge. I think people here say that the lift pumps have changed a couple times. My 05 engine did NOT have a lift pump mounted on the engine.

 

Thanks Superduty. I have an appointment for Monday morning (when the good diesel tech is off vacation) for my cp3 leaking. I'll ask him to test my lift pump while he's in there and I'm gonna look into the replacement pump like you have, thats not much money to ward off future problems...LCH

 

Superduty, what is your opinion about the in-tank retrofit vs going with the Walbro?

 

"Superduty, what is your opinion about the in-tank retrofit vs going with the Walbro?"

Rightly or wrongly, I am biased to the Walbro.

It is designed for 60 to 100 PSI, so a partially blocked fuel filter isn't going to slow it down or wreck it. (Which may be happening with the stock fuel pumps.) I know if that pump is turning that my CP3 is getting fuel.

Beware that if my filter ever totally blocked the Walbro would blow my filter housing lid. I broke one when I installed the Walbro and ran it without the bypass.

And I like the fact it ISN'T in the friggin tank. If my pump failed tomorrow, I can change it without dropping the tank. This is just my opinion though.

 

The CP3 are different on the 04.5 and up.
The lift pump is different on the 05 and up.

 

If you install a different lift pump or put on a helper pusher lift pump beware you have to reduce the pressure or bypass it some how, the CP3 does not requir or like high fuel pressures coming into it. I think the rating is no more than 10 PSI for the CP3 injection pump. Not exactly sure on the pressure coming in but you get the picture.

 

"If you install a different lift pump or put on a helper pusher lift pump beware you have to reduce the pressure or bypass it some how"

Yes, you do. See my post on my lift pump setup for why.

"the CP3 does not requir or like high fuel pressures coming into it."

It makes no difference to the CP3. It has a positive displacement gear pump feeding it and you'll blow up a lift pump before you damage it

"I think the rating is no more than 10 PSI for the CP3 injection pump."

I once had 80 PSI going into my CP3 with no damage. I did, however, crack my filter assembly lid. The CP3 isn't the weak link in the chain. You won't damage it with too much pressure.

 

My dealer was saying that the lift pump could damage the main fuel system? He told me what it was but i forget the name of it ..but i remember the price and it was over $2300?

 

He was right. The $2300 dollar thing he speaks of is the CP3.

 

So then you would suggest preplacing the CP3? In my situation? I just wanna get it home!! For the First TIME!!!!

 

I dunno anything about your truck or what happened.

I think CP3s are pretty tough and the damage happens from running them with insufficient fuel over a period of time.

If your truck doesn't have many miles on it, the CP3 is probably OK.