New guy here. I am looking for a little help with an issue I started having on my 2001 2500 with the 24 valve ISB.
A few days ago when I started the engine, it idled normally, but when I started down the road it acted like there was some kind of limiter holding the engine to around 1300 rpm or so. I cycled the key switch and it cleared up and ran fine........Till I got ready to leave work 10 hours later. Again I started the engine after the intake heater timed out. It idled perfectly. But when I revved it even slightly it began white smoking and stumbling like it had air in the fuel system. After the engine reached around 140 degrees it ran perfect and no more stumble at all. The next morning I went ahead and replaced the lift pump ( the old one still tested good at 9 psi at idle). The filter was also replaced. There are no warning lights on when this happens.
I work on these engines at UPS where I am a mechanic, but this is a symptom I never encountered before.
The truck has 121,000 miles on it and has never had any performance issues. This one is puzzling Me as it started all at once and does it every time it is started after cooling off to ambient temp. The intake heater is cycling correctly ( that shouldn't be an issue in 80 degree weather here anyway) what is confusing is the cause of the smoking and stumble till warmup, and then running like a top as soon as the temp gets above 140.
The thing with the rpm limiting if you try to drive it before it reaches temp is strange as well.
Do any of You have any hints or tips as to what might be going on ?
Any help would be greatly appreciated!
This is my daily transportation and I don't want to risk any damage when it might be a reasonably easy fix( I HOPE).
Thanks in advance.

 

Let me move this over to the diesel section for you. May get more responses there, as we're mostly gassers over here.

 

Nobody has any ideas?

 

Welcome to the Diesel section. Where the big boys talk about our toys...
First your truck is a 2001 so It has a vp 44 injection pump correct? Those like 16 psi +/- and few at idle. At 9 psi idle. What was the WOT psi at? If it was lower then 4 psi. I would look at the injection pump...

Is It showing any codes at all? check engine light? if so what is the code?
And no it will not show a code for low fuel pressure or lift pump failure...
What lift pump did you replace it with the factory Cummins pump? Dodge don't sell the lift pump like you have they sell a Kit that drops the pump in the tank... You would be looking at code in the line of injection pump timing of some sort... that is VP44 is dieing get a new one and get it replaced...

Also you may have a injector going. Pulling them out and having them tested might not be a bad Idea. if You cant find the problem... some places are 25-30 bucks each. I am sure you can talk to your Cummins dealer around or know a place that Work buys stuff from. Maybe they can hook you up with a dealer and not charge you too much..
I work for a Forklift dealer and know all the dealers in this area so I buy them lunch or a case of beer. I can have mine tested for free... I just had Blue's injectors tested ruff idle thought it was injectors and it wasn't FCA was going bad. Cost me a case of buttwhiper and lunch..

I expect Coaltrain and Dodgetrucker to chime in on this also... Coaltrain is a vendor here on DF so if you need parts or something Hit him up...

 

No check engine light has EVER come on . A regular code scanner showed no stored codes either.
I didn't have a way to check pressure @ WOT or under a load. The new lift pump was the one built by Carter that comes standard on the 2001 ISB W/ The VP44 pump. I have had numerous Lift pump failures on some of the ISB engines at work. Each one set a code for the lift pump showing low voltage or high/open voltage. The other code I have seen on them is VP 44 pump unable to achieve desired timing. Each one that had that code has needed VP 44 replacement. Doing the lift pump test on some @ work using the Cummins Insite program, I normally see 10+ psi at idle or while running the lift pump over ride test. The one I took off was showing 9 3/4 psi @ isle, the new pump tested 10+ @ idle. I had to make an adapter to test the pressure at idle, but no way to see the gauge while under a load ie: driving it. The truck doesn't show the symptoms I have witnessed with a VP44 failure. No codes, no rough running or smoking after initial warmup. No stumble with engine temp above 140. Runs like a raped ape after warmup. The big concern is the white smoking and stumble till it warms up. It seems like air in the fuel system, but i see no source for air to enter it, nor does it have hard start problems like it was losing prime.

I would love to hookup to a Insite program and look at performance while it is cold, but don't have access to the software except @ work, and we can't take personal vehicles on the yard or too the shop.
If it would throw a code, I could deal with it from there. I just think it's mechanical in nature, not electronic.
I have 20+ years diesel experience, but all but the last 5 years were on Cat engines. That is why I say the symptom of air in the system seems so logical to me, It acts like loss of prime, except it idles perfect when cold. I hope it's NOT the VP44, My budget can't stand that $$$ hit right now.

 

Diaphragm on the inside of the Vp 44?
sounds like its going bad or you have a injector going bad
It may work at idle ok cold, But when it gets hot it starts working correctly.. I if you have another vehicle take the injectors out and have them tested.. Mark them 1-6 so you know witch one it is. My guess its number 1 and/or 6 injector is acting up. two common injectors to go bad they sometimes get over heated. Hot spots in them areas.
if any are bad then you'll need to get your boroscope out and look down the injector holes and check the Cyl was for over fueling. hopefully it didnt trash rings or walls...


I was thinking maybe your pick up or hose had a hole in it sucking Air. But your not having trouble starting and Idling, only when you step on throttle...

10psi at idle on the lift pump... that is low.. it should but no lower then 15 or 16 psi at idle. WOT 10 psi no lower then 7 psi or your starving the vp44...

What about a fuel pressure regulator on that lift pump? does it have that? If so you might want to check into that. We dont have them on our equipment but we have vp44 on 24v with mechanical lift pumps. only 195 hp engines.. i can only recall a small handful with electric lift pumps and those are on highway use... I rarely seen them..

 

Thanks for the ideas. I already put the new electric lift pump on. Problem still exists. If an injector was bad shouldn't it be skipping? It doesn't skip even when idling cold. It only stumbles when You rev it slightly. That's when the smoking starts too. I cranked it up today and let it idle 10 minutes or so, and it ran perfect as soon as I took off.
I guess I'm down to pulling injectors and getting them checked.
I heard that the mounting boss and lobe are still on the camshaft to install the early mechanical pumps??? do You know if that's true?
Thanks again for the suggestions.

 

Hows the turbo? Wastegate? Does it feel like it is actually stumbling or just losing tons of power?

 

It will white smoke( raw fuel or air in fuel) if you rev it slightly after a few seconds from cold startup.
If You let it idle for 4 or 5 minutes after startup, it will run perfectly. every once in awhile it will act like it is being limited on rpm when first pulling off after letting it warm up, and cycling the key switch of and back on after a few seconds, and it will run perfect after that. It doesn't do that all the time, maybe every 5 -6 times you drive the first time after startup. It doesn't stumble after it is running down the road, and power is normal. I checked the compressor wheel in the turbo, no radial or axial play in it, and no thrust play either. I am borrowing a laptop with the software in it to run tests later in the week from a co-worker.
The rpm limiting almost acts like the boost sensor might be sending an inaccurate signal and the fuel is being held back. I have seen that happen on Cat engines before, and will see what the boost is reading when it happens.
This is a very strange problem that is kind of throwing me a curve trying to diagnose it. Like I said, once it warms up above 140, it runs perfect, and doesn't act up any more till it sits overnight, or for the 10 hours or so I'm at work. When I started it to go to work Monday night....... It ran perfect even without the warmup time, then when leaving work it did the white smoking thing ( only when revved above 1000 rpm or so) but ran fine after idling for about 5 minutes.
It doesn't stumble while driving at all.???????????????
Any suggestions would be appreciated.

 

this is starting to sound like a normal problem, well not a problem just normal, i have seen valves out of adjustment cause this and most can be cured up with a valve adjustment, but whits smoke and stumble while cold and a no load rev is normal, if i try to free rev mine when it is cold it wont 1500 and pops and shakes violently, bottom line, these engines dont like being cold, and need to be warmed up to operate correctly, if its only doing it when cold and no load, i wouldnt worrie about it, do a valve adjustment and see what it does,