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Executive45's avatar
Executive45
Explorer III
Apr 14, 2019

UPDATE: Hard starting Cummins ISM

Good Morning everyone! Cummins ISM. 95,000 miles. Just had it serviced, replaced water separator, filters etc. including Allison transmission service. Generally used Speedco for service but tried out a new facility in Arizona. My engine has always started within 3-5 seconds, I'll call it a short crank. After service it will still start but it now takes a long crank. That's the best way I can describe it. I'm not used to cranking an engine for an extended period of time. What could be the cause? It appears they used the correct water separator when it was changed Racor RK12963. Any insight will be appreciated....Dennis
Class A
  • Executive45's avatar
    Executive45
    Explorer III
    Apr 19, 2019
    wildmanbaker wrote:
    And I still like the "Low Rider" picture of your MH in your sig.


    :) Air leveling.
  • wildmanbaker's avatar
    wildmanbaker
    Explorer
    Apr 18, 2019
    Yes, thanks for getting back with the results. As you know, not everybody does. You are a valued member of this Forum.
  • 2_many_2's avatar
    2_many_2
    Explorer III
    Apr 17, 2019
    Thank you for coming back with the results, congrats on an easy fix! :B
  • Executive45's avatar
    Executive45
    Explorer III
    Apr 17, 2019
    Picked up the coach last night and it's fixed. When they put on the new filters one of the "O" rings didn't get seated correctly. Removed the filter, put on a new O ring and all is good again. Thanks everyone for your advice....Dennis
  • Executive45's avatar
    Executive45
    Explorer III
    Apr 15, 2019
    11178adm wrote:
    the most likely cause is the wrong engine mounted fuel filter. The cummins N14, M11 and ISM engine fuel filter must have a metal tube down the center of the filter or they will have long crank time. There are a lot of filters that will screw onto the cummins filter base but whatever they installed should cross to fleetgard number FS1000


    Thanks everyone again. After purging the system several times yesterday, I took the coach back to the shop this morning and advised them of the above and the other suggestions. They assured me they would fix it. I'm picking it up tomorrow and I'll post the results.

    Thanks again for the sage advice....Dennis
  • JackMS's avatar
    JackMS
    Explorer
    Apr 15, 2019
    If your separator is the type with the clear glass on top, there is usually an anti backflow valve in the outlet fitting. Very simple construction- a plastic cage with a ball and spring in it. Any bit of trash can cause a long crank situation, but it takes a while after shutting down to show up. If your engine is running and you shut it down and immediately restart, does it start better? If so then probably not that check valve.
  • 11178adm's avatar
    11178adm
    Explorer
    Apr 14, 2019
    the most likely cause is the wrong engine mounted fuel filter. The cummins N14, M11 and ISM engine fuel filter must have a metal tube down the center of the filter or they will have long crank time. There are a lot of filters that will screw onto the cummins filter base but whatever they installed should cross to fleetgard number FS1000
  • Executive45's avatar
    Executive45
    Explorer III
    Apr 14, 2019
    Thanks everyone so far. You've verified my suspicions. Air somehow leaking back into the fuel was my initial thought. I've only driven it about 8 miles since the service..I;ll repurge the system today and see if that helps....Dennis

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