BobOkie

2002 2500 Dodge with Cummins stick shift – no mods
I have a problem that has me and several friends that are alot more diesel savvy stumped. I’ll give it in bullet points to be brief. We work in manufacturing making big equipment stuff with diesel engines and several are hobby mechanics.

Temperature 36 degrees or above
* Truck runs fine, easy idle and good acceleration
* No Mods on truck

Temperature around 25 degrees or lower (OK so not much lower)
(haven’t tried between because when problem started I drove my daughter’s car. Obviously she isn’t happy. Temperature jumped back to mid 30's in morning and I've been driving truck to work.)
* Idle, same as above
* Driving at about 1500-2000 rpm hesitation and almost like a bucking horse at times
* pedal to the metal – major loses of power and speed
* block heater overnight – no change
* 15 minutes idle with block heater overnight – no change
* Anti-gel fuel additive – no change (it is not that cold)
* No dash lights during or after this type of operation
* After hesitation rpm needle will bounce, have to turn off to restore steady position in idle. Bounce is very small but noticeable.

Done so far:
* Changed oil and filter (it was time, didn’t think it was related)
* Changed fuel filter (Thank goodness for youtube and learning how to bleed air)

Suggestions?

cougar

Change the temp and map sensors. Mine did something like that and progressively got worse by temperature. But cold up here is COLD!

torquefan

I'd also drive it with a fuel pressure gauge installed, and monitor the pressure while the condition is both active and not active; see if you can detect anything that may indicate a failing lift pump, or air intrusion.

mini14

check for codes

SIXSLUG

Check for codes.

Know how? Key on/off 3 times watch odometer with pencil and pad in hands, record 4 digit numbers after ecm and pcm shows up.

KATOOM

You said "no mods" so based on that, to best help and understand whats going on.....
How many miles on this truck? Has ANYTHING been replaced?

You need to pull any codes within the OBD system. Yes, the key cycle trick works but a code reader will offer the best results. Write down all codes you find before trying to erase them.

Then you NEED to get a hold of a fuel pressure tester. Sometimes your local part store rents them for cheap. Hook it up to the schrader valve test ports. One on the inlet of the fuel filter and one on the VP inlet. You need to test from the test port on the VP as this will let you know true pressure to the VP.

The hose to the gauge should be long enough to allow you to hold it through the drivers window so you can test all pressures. Idle, cruise, and WOT. If the idle pressures are below 10 psi then thats not good and will most likely result in all other pressure readings being near zero.

Then take a basic everyday volt tester and check the AC voltage generated by the alternator. NOT the DC volts either..... If you're unsure how to do this then there are youtube video's to help, but understand its easy. Just set the tester to "AC" and to thousandths. The red touching the main alternator hot output line on the back and the black touching the alternator housing. You should see readings between .20 and .50 at idle. If any higher than thats bad and AC voltage is a problem.

Disconnect the batteries from everything and test their separate battery voltage while you're at it too. Bad battery condition will create electrical phantoms.

Post back what you find.

BobOkie

So an update

Problem went away when it warmed up, I had added some gel and burned through a tank of gas. Problem solved!!! I wish............

It is July/August and not cold :-) Problem started up again and seems to be getting worse. So I replace the fuel filter again(clean) and air filter (really dirty - it's Oklahoma).

Still same type of problem. Losing power above 1500 rpm, higher speeds, higher gears make it worse and more noticeable It also does not do it until about 10 minutes or so from a cold start.

Lots of reading and digging on the site.

No I didn't know how to check codes but now I do, I currently get from key switch.
P PCU
P 0500
P 1693

Which basically tells me to check codes. Stop by Autozone and code is P0126 "fuel injection pump timing failure". Counter guy has no clue and no parts show up on fix list.

Dig out some old paper work -- Replaced the lift pump in 2011 with FASS DDRP 02 (back when I had no time and money - now I have no time or money). It included a fuel pressure light kit (which has not been going on like it did earlier when I accelerated hard - mainly because I can't?). Also found this neat silver canister under the truck in the fuel line, which is an add in from the pump replacement. (does that need to be changed?)

So I'm going to tackle some of the suggested electrical items (clean battery connections, check some of the voltages, etc.) Will test out to make sure light isn't just burned out on pressure kit.

I am thinking it is likely the injector pump (2002 with 150k miles so maybe I'm lucky). Thoughts? Is that something someone can do that is reasonably mechanical inclined? Can it be done in a weekend?

Appreciate the feedback

Desert5600

Longshot...

Remove the electrical connector on the aft side of the VP44, spray contacts on VP44 and connector with electrical contact cleaner, blow dry with an air hose, apply dielectric grease and reconnect.

Solved code throwing issues for me indicating VP44 failure.