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Discussion Starter · #1 · (Edited)
EDITED TO ADD: I made another post in this thread with this info, but in case anyone is only reading the first post, I've now learned that the truck is showing the following codes: P1688, P1691 (I've posted a longer explanation below.


I tried posting something similar to this in the "emergency" section, but haven't seen any responses. I really need some help on this one... I'm in a bit of a pickle at the moment, and would like to see what you guys can tell me about this situation.

I just bought my first diesel truck within the past two weeks. Things seemed fine with the truck when I bought it: started right up, ran smoothly, no codes when my mechanic scanned it, etc.

Today I started the truck after it sat for maybe 3 days. I drove the two miles from my house to the highway at in-town speeds (0-45mph with stop and go traffic). Everything seemed fine and the factory gauges were all reading normal as I started up the highway ramp, though the engine wasn't quite up to full operating temperature at this time.

As I reached the top of the highway ramp and tried to merge onto the interstate I applied some additional accelerator. Suddenly and immediately the truck bogged down and the engine pretty much quit entirely. I coasted down a slight grade while trying to restart, and pulled over after it wouldn't start. I didn't see the gauges at the moment that it died since I was merging into traffic, but they had all been normal just prior to the merge onto the highway, with no idiot lights showing either.

After waiting a while I tried to restart again. The starter definitely had enough power, but it sounded as if the engine wasn't getting fuel. When I let off of the starter the engine would go into some sickly sort of idle that sounded almost as if just one or two cylinders were firing (for lack of a better explanation). The engine was completely unresponsive to any peddle inputs.

I tried draining some fuel from the fuel filter (using the little yellow lever). Fuel drained fine, and was definitely present. I couldn't get the truck to restart, and ultimately had it towed on my buddy's flatbed, behind his working 12valve Cummins.

So, until I figure this out I'm completely truckless. I don't own a code scanner, but will probably be able to have the truck scanned within the next day or two. I only know that there were no codes showing when I bought the truck, and I've driven it less than 300 miles (which is REALLY disappointing).

Does this sound like a bad VP44 to you guys, 'cause that's kind of what I'm thinking right now? I sure hope I'm wrong!
 

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To check for code cycle the key from off to run relatively quickly. Then watch the odometer and it should tell you what codes it has. Keep watching until the miles come back. Report back to us with the codes


Sent from my Autoguide iPhone app
 

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The conditions you reported are exact for VP44 failure and possibilly from lack of lift pump pressure. Now you know why PO was letting it go. If 2000 or later you can pull codes with 3 key on trick.
 

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that is what happend to me when my lift pump went. the vp survived. so dont condemn the vp yet. get the codes and see what they say.
 

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Well back to the typical stuff...

Error Codes?

Fuel pressure?

:confused013:
 

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Discussion Starter · #7 ·
Well back to the typical stuff...

Error Codes?

Fuel pressure?

:confused013:

Sorry, I didn't have the code information until today. My friend towed my truck for me, and he didn't have the opportunity to scan it until this afternoon. As of now I'm still truckless, and I'm hoping to get things repaired in the very near future!

Two codes showed up:

1) P1688 - he said this is a code for a "VP44 fuel injection module internal memory error"

2) P1691 - this one was said to be a "fuel injection pump calibration error"



Beyond what I've stated, I know very little about what these codes mean. These codes do bring up a number of questions for me:

Is my VP44 in-fact fully dead, or do these codes not necessarily mean that?

Could these codes pop as the result of some other type of fueling system/electronic failure, or the failure of something that doesn't require the actual replacement of the injection pump?

Per your question, Moparman, unfortunately I don't know my fuel pressure due to the fact that I haven't yet installed such a gauge. However, when I was broken down my friend was trying to diagnose the problem at the side of the road, and said that he wasn't getting any fuel from the lift pump (to do this diagnosis I think he had me crank the engine while he loosened one of the banjo bolts on the fuel filter --- don't quote me on that, but I believe that is what he was doing to try to see if the lift pump was sending fuel with any sort of pressure).

Finally, I should add that I stopped by my local Dodge dealership this afternoon, looking for a trivial part that had nothing to do with this issue. In the course of my conversation with one of the guys there, he told me that my pump may not actually be fried (even based on those codes), and that I ought to bring the truck in for a $130 diagnostics appointment, so that they could possibly "save [me] a lot of money on buying unnecessary parts". If there is a high likelihood that these codes (and my breakdown) were triggered by something less expensive than a VP44, I'd obviously like to save money. But, if the dealership is just trying to talk me into spending $130 of hard-earned money that doesn't need to be spent, then I don't really see the point!


Thanks again for the help, everyone !
 

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You didnt by accident put gasoline in her did you? Just weighing out all the possibilities. I have done that one before and had all the symptoms you are describing.:doh:Wont hurt to check.:confused013:
 

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Well $130 is 10% added to cost of repairs needed. JMHO of course.
Must verify LP pressure.
 

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Discussion Starter · #10 ·
Well $130 is 10% added to cost of repairs needed. JMHO of course.
Must verify LP pressure.
So, how can I verify the LP pressure at this point? The truck is dead, I have no gauge, and I'm fairly new to these problems. As I mentioned, my friend claimed there was no pressure from the pump, but I'm only going off of what he said (as I tried to explain, albeit poorly, in my previous post).



You didnt by accident put gasoline in her did you? Just weighing out all the possibilities. I have done that one before and had all the symptoms you are describing.:doh:Wont hurt to check.:confused013:
No, that I'm sure of. I'm new to diesel trucks, so I was exceedingly careful about choosing the right pump at the gas station. Plus, I put 32 gallons in the tank, and drove about 125 miles before the failure happened.
 

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"So, how can I verify the LP pressure at this point?"

There should be a test port on the side of the vp44, barrow a test gauge or use an old r12 ac gauge set.
After attaching the gauge just bump the starter don't crank it over.
 

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Discussion Starter · #14 ·
the best diagnosis resource on the net is at bluechip, read away and be brought up to speed

Blue Chip Diesel Performance Specialists
Thanks for the link. I've actually been reading on his site for a few days now, but I'm not sure what I'm still missing when it comes to diagnosing this problem (like: are the codes mixed with my described failure enough to diagnose this problem as a failed VP44? If not, what more should I do, and how do I go about it?).

I am a bit new to this: new to diesels, new to injection pump problems, and not by any means a master mechanic!

But, I'm not rich either, and I have a capacity to learn, which is why I'm trying to figure this out, rather than heading to the dealership with my problem :help1:
 

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Moparman1973 is right on when he says check pressure at the testport on the vp. Sometimes the fuel strainer can kinda fall apart and get sucked up into the lift pump, slowly strangling it, and killing your VP44. The unfortunate reality is that the VP44 will let go eventually during the life of the truck. the good news is thats about all that can killl it. diesels are actually easier to deal with, IMHO than gassers. No fuel, no go. If you have mechanic friends, I would 1st check the pressure at the VP44, which is probably non-existant. if you've got insufficient pressure I would drop the tank, drain it, and clean it out. replace the lift pump with something suitable, i.e a Raptor, Airdog, or Fass any of which can gotten with a bigline kit. This forum is also an excellent tool. Dig around a little, and you'll be suprised at what you find out. good luck.
 

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Discussion Starter · #16 ·
Thanks for the advice everyone... Sorry to sound like an uninformed newbie (but, well, I am).

I'll see if I can borrow some tools to check the pressure as you described. If I'm understanding this correctly, the purpose of this pressure check is to tell me whether or not my lift pump is doing its job by supplying sufficient fuel pressure, right? Regardless of those results, should I assume that the VP44 is dead at this point based on the codes that have come up, and the failure I had while driving? Or, could the results of a fuel pressure check potentially mean that I haven't killed the VP44 yet?
 

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Thanks for the advice everyone... Sorry to sound like an uninformed newbie (but, well, I am).

I'll see if I can borrow some tools to check the pressure as you described. If I'm understanding this correctly, the purpose of this pressure check is to tell me whether or not my lift pump is doing its job by supplying sufficient fuel pressure, right? Regardless of those results, should I assume that the VP44 is dead at this point based on the codes that have come up, and the failure I had while driving? Or, could the results of a fuel pressure check potentially mean that I haven't killed the VP44 yet?
My vp44 went out a couple months ago, and ultimately how I checked it was to verify that I was getting fuel from my lift pump to the injection by disconnecting the line right at the vp44 that comes from the lift pump (i have an airdog set up so this was very easy for me) and then checked my electrical connections. Finally i cracked open a couple of the injector lines up at the head of the engine and i had a little bit of diesel dribble out and that was the final stroke in my decision. I'm a poor college kid so I went on youtube watched several videos that walk you through a replacement and did it myself for about 1100 bucks including the parts tools i had to buy. I'm not mechanically inclined at all, but if you get everything lined up prior to, this is definitely a job that can be done by yourself, dont waste your money at dealer.
 

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You can also pull one of the hex head pipe thread plugs out of the top of the filter housing (the one closest to the center of the housing) and screw in a gauge there. 1/8" pipe thread. This isn't as accurate as checking at the pump, but it does tell you if your lift pump is working. The pressure at the inj. pump will typically be a little lower than the filter housing because of the restriction in the fittings between the two. Hope this helps.
 

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Discussion Starter · #20 · (Edited)
Okay, in looking at my injection pump (as best I can with the intake horn and whatnot still attached) it does not look like I have any kind of obvious test port. From what I've been reading, it sounds like 99.5 and up came with a schrader valve on the pump. I don't see a valve of this kind on the pump, and I can't verify whether or not there is actually supposed to be one. I believe I have an early 99, which might explain why it is missing (if it actually exists on other trucks).

Assuming I lack that test port, what should I do to verify pressure? And, since it seems like I'm being told that this is a critical step in the diagnosis, what pressure am I looking for? I can't start my truck right now, it's dead in the water. But, I assume you guys just mean that I'm looking for the pressure that the lift pump provides to the injection pump. Right? So, I'm guessing that I'm looking for something in the range of 5-15psi, after bumping the starter to let the lift pump run?

As I tried to explain earlier, my friend tried opening a line on the filter housing while we were at the side of the highway. He said the fuel merely dribbled from this spot while the lift pump was running, whereas he expected some spray if the lift pump was working correctly.

I need to get my truck up and running again, but I don't want to be hasty about this and buy unneeded parts, or miss a critical step since I'm pretty darn new to wrenching on diesels!

To recap, this is what I know so far:

-Truck died suddenly while driving down the road, won't restart
-Codes 1688 and 1691 showed up
-Truck sounds as if it isn't getting fuel
-No fuel spray from a loosened line at the filter housing while running lift pump
-Haven't loosened any injection lines yet
-Can't find an obvious test port on the VP44


You can also pull one of the hex head pipe thread plugs out of the top of the filter housing (the one closest to the center of the housing) and screw in a gauge there. 1/8" pipe thread. This isn't as accurate as checking at the pump, but it does tell you if your lift pump is working. The pressure at the inj. pump will typically be a little lower than the filter housing because of the restriction in the fittings between the two. Hope this helps.
Okay, now this might be possible, and I really appreciate your reply. I'm not able to get a good look at my truck right now (0350hrs, and darn dark out there -- will look in the morning), but I am looking at my Haynes guide based on your post. I see where you're talking about testing from.


Thanks for your patience with the FNG, everyone!
 
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