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Priming Cummins QSM-11s

Discussion in 'Engines' started by Capt Bill11, Oct 12, 2014.

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  1. Capt Bill11, Oct 12, 2014
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    Capt Bill11

    Capt Bill11 Senior Member

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    Any tips or tricks to priming the fuel system on a QSM-11?
  2. Capt Ralph, Oct 12, 2014
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    Capt Ralph

    Capt Ralph Senior Member

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    Pre-charging the filters usually is a big plus. Young healthy kid with big hands to work the plungers would be the next plan.
  3. Capt Bill11, Oct 12, 2014
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    Capt Bill11

    Capt Bill11 Senior Member

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    It's my understanding you do not prime the filters on the engine. Just turn the key on for 15 seconds or so, let the pump run tell it stops and repeat a couple of times.
  4. Capt Ralph, Oct 12, 2014
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    Capt Ralph

    Capt Ralph Senior Member

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    I think I'm reading key on for 15 seconds and an electric pump will primp and purge the system. I don't think so. It may not have a priming plunger on the fuel pump, but I'm pretty sure it's still mechanical.
    OR, are you thinking turning the motor over for 15 second attempts. Correct. That is why it's important to precharge the filters.
    You may want to consider a electric lift or priming pump to help save time and eliminate a possible mess.
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  5. Capt J, Oct 12, 2014
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    Capt J

    Capt J Senior Member

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    I do a service on qsm11's sometimes. I always pre-fill the secondaries and also make sure the racors are full as well. The secondaries sit perfectly verticle on the back of the engine on a bracket and can be filled to full and screwed right on. If memory serves me right they also have a shutoff valve right near the filter that can be shut as well, although it's been a while so that might be for the coolant filter. Doing that I have never had to do anything, but turn the key on and start them up.
  6. Capt Bill11, Oct 13, 2014
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    Capt Bill11

    Capt Bill11 Senior Member

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    OK, filled the Racor, did not prime the engine mount filter that was mounted high on the front of the engine as I was told that was not needed. Tried the turn the key on for 15 sec. to run the pump. No pump sound. Put the throttle control in neutral lock position and cranked it over with the throttle advanced. Engine fired up after 30 seconds or less of cranking. Let it run at high idle for 15 plus minutes then took it up to max RPM for several seconds. All good now. Thanks.
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  7. Capt Ralph, Oct 13, 2014
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    Capt Ralph

    Capt Ralph Senior Member

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    Sounds good.
    Question; you were told precharging the filter was not needed by a Cummins shop or heavy? Any explanation for that reasoning?
    SOP is precharge but if there is something to it, I'm open to learn something new also.
    It worked for you and that is good.
    30 seconds of cranking continuous may have been avoided with a precharged filter. Starters need luv and a easy life when possible. Spares are not on every corner.
  8. Kafue, Oct 13, 2014
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    Kafue

    Kafue Senior Member

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    An electric prime pump is always a good addition to any engine.
  9. Chasm, Oct 13, 2014
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    Chasm

    Chasm Senior Member

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    The reason not to pre fill the final fuel filters of some engines is that there may be junk in the fuel that blocks or damages the pump and/or the injectors. Say common rail engines with 2 micron final filters.
  10. K1W1, Oct 13, 2014
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    K1W1

    K1W1 Senior Member

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    I have primed plenty of fuel and oil filters albeit with clean product and never caused any damage to the rest if the system.

    If you fill one with dirty fuel then you deserve what happens.
  11. Capt J, Oct 13, 2014
    #11
    Capt J

    Capt J Senior Member

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    I too have done the same and agree. I am not going to put a secondary on that is dry, even the pre-common rail MAN filters that mounted at an angle I still pre-filled 2/3 of the way before putting on, opening the bleed screws and hand pumping it.
  12. Chasm, Oct 14, 2014
    #12
    Chasm

    Chasm Senior Member

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    And there we have the difference between the reason why something gets written into a service manual and what you can get away with if you know what you are doing. :D (And more importantly knowing what you can't do.)
  13. jhall767, Oct 14, 2014
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    jhall767

    jhall767 Senior Member

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    As long as you are pre-filtering the fuel down to two microns before filling the filter you should be ok. If not why would you put "clean" unfiltered fuel through your injectors? The engines have a filter priming sequence - follow it.