I have had this 2001 Dodge 3/4 ton 4x4 5.9 Cummins 24 valve turbo diesel for almost 5 years . I'm a plumbing contractor so , I keep this truck loaded with tools , supplies , and I pull a 3500 lb Bel-she trailer with my mini-excavator a couple of times a month. I ask a lot from this truck, and it's a hoss. 296,000 miles auto transmission. My problem I'm having is that the past few months , the truck will be going along , and suddenly just fall flat on it's face, and right before you think it's going to die , it picks back up.That was before last week, I went to a job , limped it half way there and all the way back. I put in in my shop and started checking anything and everything. I replaced all of my battery leads with some 00 welding leads + and - both I checked the codes by using the key in ignition and on off, on off, on P1693 is the only one I'm getting , now. Earlier in the week I got the 1693 and P0122 . Replaced the APPS , same symptoms. Starts right up , idles great, start to push the accelerator , and it will almost jump up to 1400-1500 RPM and fall hard right back to about 1000-1100 and stay right there. It smokes when it is put under a load . The truck had a quadzilla adrenalin chip in it when I bought it. I disconnected it , when it started all this . Truck is bone stock,vp44 rebuilt 3 yrs ago. I've worked on and researched this to where I almost want to sell my truck. Please help me

 

Well if you have done a lot of research on these trucks you have probably seen where these injection pumps like to have good fuel pressure at all times.
Do you have a fuel pressure gauge?
What is your pressure?
Do you have an aftermarket fuel system?

You said the truck fell on its face now when you said bad do you mean that The pedal almost felt dead?

When you free Rev the truck does it spoke it all does it pop?
Hopefully we can keep this rolling get you figured out as soon as possible

 

I just bought a gauge last night. Install today . I also installed a airtex fuel pump last night. By fell on its' face , I mean, I could be going any speed at all and all of the sudden it's like it just dies. No power no acceleration, nothing until it picks back up. It has never died on me though. When it's at idle , it's fine , but as soon as you try the accelerator , it's like it wants to go , it revs up to 1400-1500 rpm real fast , but just as fast it goes back to a constant 1000-1100 rpm . No more no less. It has only a couple of times "popped" right at first when I started it, but then idled fine. I have checked every wire in the engine compartment. Ground wires too. I'm really stumped . I've seen a couple of similar threads on these symptoms , but I have not seen a solution . I would be very grateful for any help I can get. Thank you for your time. There is not enough time in the day , I really do appreciate you allowing me to occupy some of yours !!!

 

The truck does smoke when you raise the rpm. I haven't even thought about taking it out of the garage. It probably wouldn't make it like it is. Like I said , the truck is all stock, and I do keep a good maintenance routine. The pump that I got has between 14 and 29 psi. Do I need a bigger pump? I'm kind of new to a diesel if it's not able to dig . It must be the plumber in me

 

thats good pressure, its when they start too fall below 13-10 that you should worry, or go higher than low 30's at WOT, especially being stock. The popping is strange, like a backfire pop? Can't help but think the pumps the culprit, thats a weird spot for it too be idling at 1000-1100, is your foot still into it when it does that? or only after you've let off?

 

There's a small range of fuel pressure that you need to be operating in while using a VP 40 for anything below 13 PSI is considered bad anything above 20 psi at Idle is considered bad. 13–20 is all the range you have to play with

I agree this sounds like a injection pump issue

 

The truck usually idles at about 750 + . When I was talking about it idles at 1000-1100 I meant with your foot in the pedal. Not 1000 at normal idle. I picked up a obd2 last night , but it wouldn't read everything I got P1689 and P0216. The other day it was 1693 and 0122 from the dash . When I had to change the pump last time , it wouldn't run at all. Why would it run and idle if the pump is bad ? I have a friend that's bringing his scan over this morning. I'll report back with the findings . Thanks again

 

Well , sorry for they delay on the fuel pressure . I checked the pressure last night , just a footnote , the truck stars up better than it has in a year or so. Fuel pressure at idle is 8-10 psi when you open the throttle it goes down to 5-6 psi. the truck is not throwing . My friend brought his scan tool over the other day , the only codes were 1693 , 0216, I really need get this thing fixed , injection pump or whatever , the truck needs to go to work. Thanks for any and all advise and suggestions .

 

I would start with a new lift pump. There is a bunch of them out there, take your pick.
Then if that fixes it great! If not than you may be needing a vp-44

 

This truck does not have a lift pump , did not come with one . It does have an aluminum "block" that bolts right up to where a pump would go , but it is only a pass thru for the fuel line . I did put a pump in its place but it did not make a difference, But I am not sure of my wiring of the pump. Since there was not one (stock) so no wiring harness. I tapped the pump wires into the fuel heater , on the side of the fuel canister .I figure I'm not going hunting AGAIN this weekend and fix the buggy