Sean S

Hey All,
My truck *suddenly* developed a problem about a week ago where it *suddenly* falls on it's face when towing and then picks up again (after letting off the throttle and blocking a freeway lane while coasting at 10mph).

The previous day, I was towing 15K through the mountains without any sign of trouble at all.

Basically just towing the empty 6K Gooseneck home from the 2000 mile trip it just decided to stay running, but loose all power on the slightest grade. Now having nursed it home, it will run normally unless I put on a trailer and hit some sort of grade...then it starts failing again....runs/pulls/.....runs/doesn''t pull (repeat).

Anyway, I've now read what seems like 100 pages of LP/VP44 posts and cannot seem to realize a solid solution.

S000000.......

I go to my local Cummins shop and say "seems from the internet fellas that my lift pump is bad and possibly my injection pump".

The response I got was that the lift pump only runs to prime the VP44 at startup and rests at all other times and the VP44 does *all* of the work the rest of the time.
This didn't (and doesn't) sound right to me when half the people on this board are claiming different fuel pressures at Wide Open Throttle by changing their lift pump arrangements.

The Cummins tech went further and stated that if my VP44 was bad, that I'd have been towed in instead of driving in.
This again doesn't sound like it goes with the flow (excuse the pun) of the post in this forum.

I also got the..."it's alive or it's dead" statement regarding the LP.

Now, to make this little twilight zone episode even stranger, I somehow wandered outside the service desk area and struck up a conversation with a tech who was working on a big rig in the bay and he said exactly the same thing as the first guy!?

Well of course this make poor little me have a heck of a time trying to diagnose my power loss problem because I don't know who to believe.

Now I'm more in the guessing (actually the praying mode) and just replacing stuff in order of cost and ease instead of having a solid grasp on how the system work and thinking it out (not my style, but you do what you have to do).

So far, I replaced the fuel filter (no change)...

I installed a pusher pump *below* the stock LP (no change)...

I cracked my water separator valve while bumping the starter and poured a good gallon of fuel on the ground (well, I know it pumps something so it's not "dead")


So, can your VP or LP be "almost bad", and can an "almost bad" LP that makes fuel puddles real fast be the cause of my symptoms?

Will installing a pusher behind the original pump be useless because of check valves or restrictions in the stock LP (and would it matter if that LP was good or bad?)?

Is this just classic VP44 is about to die and all this pusher pump, holley blue, yada yada just wishful thinking?

I swear these trucks are voodoo. I get a different answer from absolutely everyone. I read ten different opinons on different forums and 10 different answers from different Cummins and Dodge service techs (which are different of course than the forum info. Much seems like speculation, peer agreements and such and the solid facts are contridicted by even the next certified factory tech as the last I spoke to.

Of course the basic goal is to get it fixed without fixing the wrong thing and hopefully it will be something other than the most expensive item....but *if* it's going to be the most expensive item, then screwing around with the fuel tank lines and such is only worth possible peace of mind in the future.

I cannot be the only one who has gone through this frustration.

OK, well any help would be truely appreciated and the quicky question is really if the Cummins techs at my local branch are high on crack or not.

Thanks Much
Sean

Stamey

If anyone tells you that the LP only runs to get started and the VP44 takes over, they ARE smoking CRACK!!
The VP44 is lubricated AND cooled by diesel fuel, unlike the previous P7100 pump, which was cooled and lubed by engine oil. Since it must have excess fuel flowing through it to get its lubrication and cooling, if your LP is not doing its job, then you are slowly killing your VP44. Ask people you talk to about how the VP44 is lubed and cooled.
As far as your LP, let's start with your flow. That doesn't really mean anything because there is no restriction when you have the drain valve open. The pump might be weak, and they can get weak, but you wouldn't know without a pressure gauge.
My LP just went week before last. It did all kinds of interesting things, but kept running, just with 4 psi at idle. This means it was flowing what the engine could consume, plus enough extra to cause the pressure to rise to 3 psi. Of course, this isn't much. I switched over to the FASS and pressure is ALWAYS 16 psi.

Concerning your power problem, I'm not sure about that, so I won't comment on it.

Chris

PS. Another thing about the LP. Dodge replaces them under warranty when they don't pump, so you KNOW they are required as a dealer is not gonna do any more than neceaary for warranty work. Anything under 8 psi at any time, Idle, WOT, means it's time for replacement.

torquefan

As an auto/diesel technician, I am very glad I have the equipment and training to do all my own diagnosing. I have witnessed many poor quality diagnoses and repairs attempted by my colleagues, so I understand your frustration. I can attempt to steer you in the right direction, but without diagnostic equipment, you are still at the mercy of who will be doing the final repair. I hate to see you throw parts at it, for obvious reasons.
The lift pump is very necessary under load. True, the VP has some suction and it will run on flat ground with a failed lift pump. Up hill you will notice a miss and white smoke at higher rpms. I think you ruled out this problem with the helper pump and cracking the separator valve.
The APPS sensor can commonly fail and cause a situation where you drive along under load, then suddenly the throttle will "go dead" and the truck will go to idle and not respond to the throttle pedal. This may last a moment then go right back to normal. It usually will set a code in the ECM.
The crankshaft position sensor can also fail intermittently. I believe the truck will still idle/run at low RPM's, and the tach may act erratically or drop to zero. This should also set a code in the ECM. Sorry I can't remember all the symptoms, it's been awhile for this one.
We also saw some problems with the main electrical connector on the early VP44's. You can disconnect it and make sure none of the female terminals have spread.
A guy with a fuel pressure gauge and a scan tool would be a big help in this situation. These are the most common problems I have seen. It's true, the VP44 may be on it's way out, they can start failing intermittently. I hope this helps a little bit.

Sean S

Well, I have to admit that I left out a couple detail simply because the whole scenerio gets too complex for anyone to attempt a reply.

I'll throw 2 or so more wrenches into this mix and see if any lightbulbs light...

The *truth* is that I dropped off my 15K trailer and load and drove empty through some mountain with no problem. Up near some cold summit in the middle of the night, the alternator stopped charging (later determined to be brushes).
Being very tired from driving, I shut the lights off and continued to run the truck to stay warm as my wife and I fell asleep. While the truck was still running, I disconnected one battery so I would have one starter batt' if the first went completely dead.

I was awakened by a short sputtering and coughing of the engine just before it stalled out (I may have still been dreaming, but I thought I caught a glimpse of the volt meter needle sitting far left (or 8vdc...or perhaps dead resting).

Anyway, before I go any further, please let me say that is was freezing and this was an emergency effort to stay warm and the rest was an attempt to get off the mountain....

Sooo...

I get up, go switch battery leads to the (hopefully) charged battery and the truck by some grace starts (and I mean on the revolution where it either starts or quits).
I start to run it off the hill with my voltage dropping by the minute. Sadly, it becomes evident that the truck is not going to make it to any town...let alone Cummins, Dodge, or even farm mechanic.

Because of this, I broke out my old school Mcgyverness and full fielded the alternator by applying a jumper from the battery to the field...yep...120amps.
I guess the full field treatment was enough to gap the just failed brushes.

Anyway, 2 or 3 hours later I was in a town and had smoked 2 rather expensive batteries and who knows what else, but I was in a town.
It was suprizing to learn that no Dodge dealer (or any other autoparts store) within 200 miles had an alternator, but after more hourse of nursing the truck around, I found a guy who would put new brushes in it.
I thanked him and took off down the freeway, but several miles later my voltage was still climbing (it was low to begin with from the new battery I had to install).

Around 16 volts my ABS light came on and I realized the horror of the night's events... I had fried my PCM or at least the voltage regulator section of my PCM.

Ok, now it's another 300 miles to the next 2 Dodge dealers who I later found out need 3 days to get a PCM (ummm..and a load of cash). In the lot of them I couldn't find a tech who even knew what "full fielding" was.

Well heck, I gave up and after some thought put a tail light bulb on the ground side of the alternator circuit to act as a shunt resistor and got the thing into range. With a little practice and generous cruise control, I could regulate the voltage with my heater fan setting. A little later the system got tired of the fluctuations in my first attempts at regulation and jumped (or bridged) a plate or two of my new battery and now I was running hot again so I had to add yet another tail light bulb in series to get the voltage down.

OK OK, so the point is that aside from shorts, spikes, and wild loads and fluctuations, I thought I'd tell the story.

Now, at this point, I've got the empty truck running pretty well but I have a planned stop to pick up a 25' GN on my way home (I'm moving, I'm not a commercial or hot shot hauler).

So I hook up and off I go for a couple hours before I hit some mild long grades and BOOM...loss of power similar to this APPS symptom.

Now for "my" semi-analysis....

I had run that truck near 20 K (towing) without changing the fuel filter. I have had the TPS (or APPS) problem before. It came back shortly after doing the battery removal thing and I took the truck and had it flashed and at the same time change the fuel filter, and no such problems since...until now.

So, possibly the fuel filter was in desparate need of replacing and it's coicedence... (so far proven un-true)...

OR...

The major electrical storm fried my computer (which I cannot figure out if it even controls the pump timing or if that is handled completely by the VP44 ECM)

OR...

The low voltage for many miles ran my LP too slow and wiped out either the LP (due to heat) or the VP44 (from not enough voltage to the LP)... (BTW..Cummins tech LA says 8v is more than enough but I may have had less on the mountain in my sleep)

OR...

The electrical storm (I like to call it that) screwed up my APPS/CPS or some other sensor(s).

OR ..???????

Interestingly, what we (or probably just I) may learn here is that if you run your truck without the charging system until it dies, that you may destroy your VP44 due to no pressure to the VP44 (although perhaps at idle the VP44 can pump enough to save itself).

Is that complicated enough? It gets worse...

I go to Dodge and get the codes and I've got:

P1689
No communication to the injector pump ECM

P0216 (yeah)
Fuel Injector Pump Timing Failure.

These code on their own may have mysterious possibilities, but add to this that a Dodge dealer along the way (who didn't seem too comfortable with a scanner) disconnected and checked every wire to the PCM....and don't forget that I probably ran the voltage of the system down on the mountain to where the computer actually shut down and killed the engine.
So basically codes that normally meant at least something, could possibly have been caused by electrical problems and disconnections along this journey.

It was the Dodge...um...customer service rep..um tech...um something or other who actually read the codes when I got home. After he figured out how to plug it in, he was able to read those codes and then clear them but had little else to offer. ...Oooops, sorry... he *did* go to great lengths to explain how a bad LP would wipe out a VP44. Confidence now lost I moped home and here I am.

Now having posting this addition to my original question, I'm starting to feel like *I* am high on crack, and I suppose that now I have pushed this into the arena of "well, you'll have to have it diagnosed from top to bottom". Sadly, that is over a grand just for an answer from someone who doesn't even seem to know what an engine does beyond make codes for his little toy to display.

Did I mention my truck has 275,000+ on it and I have absolutely no idea when (or if) the LP or VP44 were last replaced? HAHAHAHAH!!!!!

I guess at this point I'm open to suggestions, specuations, jokes, and metaphysical diesel engine diagnostic practices.

Thoughts?

Sean (and his pretty red truck)

Dieseldude4x4

Phew, and I thought I had to do some rough things in the past to get a vehicle home.
Good luck.

duner

man, if the electronics in these trucks will take that kind of abuse and still get you home i'm impressed.

rangerst

Whew Sean, makes me think about buying a nice 1993 ctd pop the clutch battery optional model ! I wish you lol in the "quick" diognostic resolution you seek. The come and go heehaa sure sounds like the vp44 description discussed by www.bluechipdiesel.com/Bosch-VP44.htm. You might check it out.[sorry, I don't know how to do "click here" stuff!] Like Paul Harvey I want to stick around for the rest of the story and just to add a littie more mix I read here somewhere that the valves need to be" decarboned" after even a short extended idoling period whatever that means... good luck

Sean S

Duner,

Although I'm usually on this board begging for help, hopefully my experiences will offer something to the group.

In this case, I have been told (although rumor but likely true), that many of the computer systems on the truck have, and will resort to a "duty cycle" if the main (and touchy) system fails.

In other words, for probably nothing more than liability issues, HAL your super computer which gives you that extra mile per gallon and extra 2 horsepower will turn over it's duties to a more solid (and simple) backup system as it waves goodbye.

Due to the fact that my voltage regulation section of my PCM is gone, I actually now have a 100 amp CADILLAC alternator running the truck now.
Since I am moving, I don't have the time to find the best (and most cost efficient) way to replace the computer.
The factory alternator is basically a regular Nippondenso unit with a difference control voltage setup where the field is regulated on the *negative* side of the field (by the computer) instead of the positive side (like most alternators would be).

So, I'll offer this to the group...
Your trucks...in a pinch, will run just fine on a standard AC delco or whatever internally regulated alternator (many frames will actually bolt up just fine, as will the pulley)...BUT MAKE SURE TO DISCONNECT THE FIELD PLUG ON THE STOCK UNIT BEFORE DOING ANY TESTS OR HOTWIRES...because since the regulation takes place on the *other* wire, you will fry your PCM doing something that can be easily done on any standard system.

In layman's terms, if your alternator goes out and you cannot find a replacement but need to get home, unplug the factory unit, remove it, and find an autoparts store that has an internally regulated whatever with a frame that will bolt in, and do not try to hook that up to the stock regulation wires (just hook it to the batt' because it's internally regulated anyway).

At least this will get you home and you won't fry a $1500 PCM doing the oldest charging system test in the book.

Ok, and now my little rant ('cause I always include one)...

Ya know, it almost feels like they planned on my blowing that PCM as punishment for trying to fix it myself....a trap. They could have designed it in 10 different ways based on the long standing system, but they did it in the one way, that the obvious test and/or emergency fix costs you a couple grand.
I'm not exactly an "ol' timer"...I'm 36, but I grew up around them and I've learned how to get a vehicle home (and even sometimes repair one).
I've often amazed my friends by getting them off the side of the road with a coat hanger.
Now, after all of that knowledge, I have to feel stupid compared to a kid who drives a Honda to his job in the Dodge service department and doesn't even know why what he is replacing is fixing the problem.
Some would say "Welcome to the new world" as if cars had become so technical that it takes special training and rocket science to work on one, but in my opinon the reason for these designs is to keep new carpet in the showroom since it could have been designed to do the same thing and still be forgiving of the home/emergency mechanic.
Cars and Trucks have now gone the way of the computer printer where (because of the competiveness of the business), the profit of the truck is realized after the sale. A computer printer is an extremely complicated and hard to manufacture piece of equipment. At $120, does anyone think they are making a profit?
All one has to do is run out of ink and they will quickly realize where the profit lays. Ink, PCM's, Alternators that have a "slight" difference in the control scheme...etc. Auto manufacturers have made their product proprietary in parts and service under the vail of getting that extra 2% performance (where a truely good design could have done that using universal parts).
More money to the service/parts department means more/bigger/nicer dealerships and hence more sales. The added bonus is that they can hire techs who passed the OBDII test 2 weeks after passing their driving test.
Gotta problem with that?...too bad.
Inject aftermarket ink into your printer cartridge....no warranty.
Stick a LP that actually works on your engine...no warranty.

Modern printers are actually designed to malfunction unless using the ink sold by the manufacturer. It is a constant battle to redesign the printer to fail as the aftermarket ink manufactuers strive to reformulate an ink that gets around this intentional failure.

I guess none of this would bother me so much if not for the commercials that try to make you feel warm and fuzzy and like the corporation actually cares about you.

(rant off)

La La La--La La


Sean

Haulin_in_Dixie

The charging problem is easy and cheap to cure. Just eliminate the PCM wiring fromt he altinator and add a 1970 or so regulator. Do add a ground wire from the alternator to the regulator. Mine is set up that way and it works great. The wiring is simple and the alternator is nothing other than a stupid alternator like mopar used to use for years. The rest of the system does not care. Pick up the 12+ for it from the ASD relay wire as it goes into the PCM, no fuses or other required, the lead is fused.

Sean S

Haulin',
On my 99, the field is provided with a full 12v and the low side is regulated.

I tried exactly what you are saying (regulate the high side with a universal), but it did not work. Some internal resistance in the alternator kept the universal regulator from passing voltage.

I agree that the alternator is "dumb", but being that the computer regulates it from the low side should make it difficult or impossible for a standard regulated to regulate from either side. Apparantly the low side should be producing about 5v or less. That 5v would be at full charge. A standard universal would interpret that 5v as waaaay under voltage and try to get more charge going.
This is exactly what happened when I tried it too. Try to use the low side through the regulator and it overcharges. Try to use the high side of the field and the low side to ground, and it doesn't energize the field due to whatever resistors are in there that normally provide a 5v max to the computer.

(sigh)...even *I* cannot read that.

Long story short, I tried it...no worky... and I'm quite curious as to why it will work on yours and not on my system?

Sean

Haulin_in_Dixie

You must have had it hooked up wrong. ASD to the hot terminal of a 2 conductor electronic regulator, continue that wire to one of the alternator terminals. The other terminal to the other terminal of the regulator. A ground wire from the alternator to the case of the regulator. It is just a 12v excited dumb alternator. Hooked up right it works fine. If you can't make it work, if you crossed the regulator wires it will short out the regulator, I trashed one setting it up. You could also just use a buzz box, 60's regulator, to one terminal on the alterantor and the other grounded like the older units operated. Wiring diagram from an old repair manual to check yourself. It works, no question. Exciter is just a coil through the two brushes at 12v regulated to control the output voltage.

You must completely disconnect the PCM wires.

kingofdodge7131

So, what is "full fielding

wannadiesel

Sending 12 volts through the field circuit of the alternator. Usually done to diagnose whether a charging problem is in the regulator or the alternator. If the voltage jumps up when the alt. is full fielded, the regulator is the problem.

kingofdodge7131

and how do you go about doing that?

wannadiesel

Why, you trying to blow up your PCM and batteries? Just ground the field terminal that goes to the PCM, the PCM regulates by pulsing the ground connection rapidly, if you jumper that connection to ground you get 12 volts through the field. Make sure you've got a good load on the system, though. Turn on all the lights and set the heater fan on high, and don't rev the engine. You can crank out some serious voltage with a full fielded alternator.