Forum Discussion

retiredtraveler's avatar
retiredtraveler
Explorer
Nov 02, 2015

Sluggish acceleration

We own a 1998 HR Endeavor. It has the 5.9 Cummins and 6 speed Allison tranny. This situation happened once before, but I do not recall the specifics. This morning I was bringing it to my mechanic for some electric maintenance. On the way there is a fairly steep downgrade leading to a stop light. I used the exhaust brake going down the hill. Once the light turned the acceleration was extremely sluggish, as in 0-15 MPH in 15 seconds. Once up to speed a bit all was normal. I encountered one more stop light with same result. After the maintenance was done everything was normal. Is this common with this engine/tranny? This is no speed machine but normally I can get out of the way at least.
Class A

8 Replies

  • holstein13's avatar
    holstein13
    Explorer
    Nov 04, 2015
    I have programmed my exhaust brake to come on every time I tap the brake pedal and to turn off every time I touch the accelerator. Furthermore, I programmed it in two stages to work with the cruise control to keep me within a 6 MPH zone of speed going up and down the mountains.

    I think my new settings are ideal. It's a wonder to me that chassis manufactures don't simply program all Cummins engines this way right out of the gate. No worries, however. It's a simply fix any owner can do.
  • Blaster_Man's avatar
    Blaster_Man
    Explorer
    Nov 03, 2015
    With any acceleration or fuel issue, my first attempted fix (the easiest and maybe cheapest) is always replacing the fuel filter(s). Might have to do it more than once.
  • diplomatdon's avatar
    diplomatdon
    Explorer
    Nov 03, 2015
    Plugged fuel filter is a possibility. Engine requires more fuel when pulling like from standing start or climbing grades. Cheap and easy thing to try. Get new filter, prefill with fuel, remove and replace old filter. I would dump old filter into a container, and cut open old filter to look for contamination.
  • retiredtraveler's avatar
    retiredtraveler
    Explorer
    Nov 03, 2015
    Thank to all for the replies.
    I would think plugged fuel filter would show up when cruising under load. The engine runs fine when cruising.
  • wolfe10's avatar
    wolfe10
    Explorer
    Nov 03, 2015
    retiredtravelers2013 wrote:
    Do most of you leave it on at all times?


    Will get a wide range of answers to that one. I do not, but use it almost every stop.

    And, if it was not the EB hanging up, the next "most likely suspect" for loss of power in a diesel is a clogged fuel filter. Cheap "diagnostics" to just change it/them.
  • retiredtraveler's avatar
    retiredtraveler
    Explorer
    Nov 03, 2015
    Thank you for the answers. I do not use the EB a lot. It is however only 2 years old. The old one was rotted out so I had it replaced. I will attempt to lube it. Do most of you leave it on at all times?
  • donn0128's avatar
    donn0128
    Explorer II
    Nov 02, 2015
    EB is sticking closed would be my first guess.
    Do you leave your EB on at all times?

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