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Dave_Pete's avatar
Dave_Pete
Explorer II
Oct 16, 2015

5.9 Cummins Stumble

Have been experiencing an assumed fuel problem.

2006 Dodge Ram 5.9L Cummins turbo diesel. No check engine lights.

Increasing, and intermittent (becoming MUCH less intermittent) stumble and rough running under LIGHT acceleration. When the problem occurs, it almost feels like it doesn't accelerate as well under heavy demand either, but that is hard to tell - stills runs quite well at higher demand and is pulling an 8000+ lb trailer up hills quite well (I'm away from home base). The stumble seems more to be during light throttle and between 1100-1800 RPM and at speeds up to 50. At cruise (1600 RPM) a slight stumble, but not really bad at all.

Also had a few episodes of white smoke and rough cold-start idle a while back. Since then I've been using "Howes Lubricator - Diesel Treat" because at THAT fuel stop it was the one on the shelf that was for fuel injector cleaning as well as diesel conditioning and anti-gel. After a very short time, no more episodes of rough cold idle or evidence of white smoke. But still - the other light acceleration issue.

I discovered a light oily condition around the fuel filter housing screw-off lid and backside hoses, so checked the lid tightness. Yep - I failed to tighten it more than hand-tight at the last filter change! The stumble had never occurred before.

This morning I tightened it and checked the other fuel line fasteners at the pump and at the filter housing. Was able to get the housing fasteners snugged a little (not too much, but they needed it just a little) and the pump's are tight enough.

I will drive today and check see, and post new reality. I don't want to start dropping into expensive dealers and shops to start troubleshooting unless it is really necessary.

I'm away from home base and I don't have a home base diesel mechanic anyway.

Questions...

What might be my causes?

Might a loose filter housing create a condition (higher/lower pressure/suck air/etc.) prior to the pump that might cause the condition at light throttle/demand?

Can driving a little longer on a stumble like this create "serious problems"? In other words, does this thing need to go into the shop immediately or since it's not acting up at higher demand/load am I okay to continue driving and check the results today of that tightened filter housing to see if that did it?

Would the earlier intermittent condition perhaps be injectors getting cleaned up and now dropping of pieces of **** like gall stones? If so, maybe I just have to live with the stumble until it cleans up? Like I said, there seems to be a worse/better stumble at different times, even to the point where the problem was hardle noticeable.
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  • Dave_Pete's avatar
    Dave_Pete
    Explorer II
    Oct 20, 2015
    Well I didn't mean to make you mad. I do understand the point you were trying to make between the lines.
  • mkirsch's avatar
    mkirsch
    Nomad II
    Oct 20, 2015
    Dave Pete wrote:
    It makes me wonder in this day of sensitive voltages and computers, just how many injectors, etc. have been unnecessarily replaced at great expense because of the lost skill of troubleshooting and time sensitive shop policies.


    Except I would chalk up your discovery of the issue to dumb luck and desperation, not troubleshooting skill.

    But it does boil down to a matter of dollars and sense. Would you rather the dealer spend 10 hours of time at $100 per hour fiddle-farting around troubleshooting, then replace the $750 part, or just replace the %$#@ $750 part in an hour or two because the computer said so?

    $1750 is a whole lot more expensive than $950.
  • Dave_Pete's avatar
    Dave_Pete
    Explorer II
    Oct 20, 2015
    Yeah Joe, my results don't answer all issues. BTW, I'd avoid WD40. It can make immediate miracles, but leaves an oily residue that can attract dirt and possibly cause future erratic electrical contact. Stick with electronic components cleaner and dielectric grease on these sorts of connections. Both are readily available.
  • okiejoe's avatar
    okiejoe
    Explorer
    Oct 20, 2015
    Good to hear, if mine starts to stumble again we'll check all the connections and hit them with WD40 too, But this time like I mentioned the dealer checked all electrical connections and Harnesses and the #3 still failed and then I took the injector to the diesel shop that actually installed it and they put it on their tester and the electrical solenoid was dead so it was actually the injector this time. Good travels to you
  • spud1957's avatar
    spud1957
    Explorer
    Oct 19, 2015
    blofgren wrote:
    spud1957 wrote:
    Weird. Based on the posts from a few of the Cummins fanboys, I assumed they were "bullet proof" and nothing ever goes wrong with them. Huh :h


    Well it wasn't turbo, head gaskets, or a $9k high pressure fuel pump failure so I would consider it a pretty minor problem :R


    More of a tongue in cheek comment.

    Since I'm considering a Ram, I've been over at the Ram Forum site. Turbos, gaskets and fuel pumps fail on the Cummins as well.
  • Dave_Pete's avatar
    Dave_Pete
    Explorer II
    Oct 19, 2015
    Dave Pete wrote:
    jmckelvy wrote:
    Another electrical harness to check is the one running next to the AC compressor. There have been reported instances of chaffing of some of the wires in the harness and causing similar symptoms.


    Thanks Jim. I'm going to look at that when the sun comes up.


    Well I located a few smaller harnesses near there, but all looked secure and we'll protected with loom.
  • Dave_Pete's avatar
    Dave_Pete
    Explorer II
    Oct 19, 2015
    I also want to clarify, I used off the Walmart shelf "bulb grease" (in automotive), not dielectric grease. Although I'm assuming they are one and the same.
  • Dave_Pete's avatar
    Dave_Pete
    Explorer II
    Oct 19, 2015
    jmckelvy wrote:
    Another electrical harness to check is the one running next to the AC compressor. There have been reported instances of chaffing of some of the wires in the harness and causing similar symptoms.


    Thanks Jim. I'm going to look at that when the sun comes up.
  • Dave_Pete's avatar
    Dave_Pete
    Explorer II
    Oct 19, 2015
    Thanks for all who cared and tried to help.

    It makes me wonder in this day of sensitive voltages and computers, just how many injectors, etc. have been unnecessarily replaced at great expense because of the lost skill of troubleshooting and time sensitive shop policies.

    As a High School senior in the late seventies in my Vocational Auto Mechanics three period class (yes, I had a pretty awesome senior year) we started getting an idea of what was coming in the automotive industry. I didn't ever think I would understand a computer, let alone own one (several?). Electronics was my dad's thing - and his was tubes changed to transistors. Huh? Resistance, etc.? I had a two by four kind of mindset. I chose a different line of work.

    But mechanics always remained a hobby and a necessity to making a family budget work. Man we saved some money over the years. Always preferred OEM over customization.

    But my mechanics instructor gave such good concept lessons, I still use them today, all the time. Troubleshooting! (Thanks teachers BTW).

    Then when I got the old Willys and read some books, Granville King (wrote the Jeep Bible), always said in troubleshooting, it is more often ignition than fuel, and I discovered he was right on more than one occasion. He also said, when there's a problem, what did you work on last? Start there.

    That's what I did here; where had I been messing? That small heater hose, and that fuel filter. Look at it, think about it. Again, the ideology worked out and this time I was saved, even though I don't know diesel as well as gas.

    It always bothers me when the Optician tries to mark your eyeball location before adjusting the frames to fit your face. Cart? Horse? Must we always risk offending by telling someone their job? Old people have wisdom. Youth! Learn to listen, learn to think! And don't let my generalization offend you!

    But it's the same in a shop. Sometimes. Other times... well those guys really save my bacon, like the guys at the Big-O tire store the other day when I really thought I had stepped on it big time with some lug nut studs.

    I won't say, all's well that ends well, but I will say, I'm happy.

    I discovered dielectric grease many years ago when I changed a tail light bulb. I thought what dumba$$ had greased an electrical socket? I discovered electronic electrical cleaner sometime later. Again, today's sensitive electronics in the harsh vehicle environment. Well, I learned something new to add to the wisdom bank this time. :)
  • DirtyOil's avatar
    DirtyOil
    Explorer
    Oct 19, 2015
    blofgren wrote:
    Dave Pete wrote:
    Well today was the test. The truck ran awesome. The problem was those electrical connections. I also cleaned and greased two more connections where the head and valve cover meet on the driver side. Each have 6 connections and I assume associated with the valves. Smooth as creamed butter now. I'm not excited. I ecstatic


    That's great. Glad to hear you got it fixed easily and inexpensively!



    X2 good find or work? :B

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