Cat 3116TA Fuel System Lesson

Discussion in 'Diesel Engines/Drives/Transmissions/Props' started by ttmott, Jun 6, 2013.

  1. ttmott

    ttmott Well-Known Member GOLD Sponsor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    Here is a bit of information on the Cat 3116TA's that probably not too many might know about and is comparatively inexpensive to correct.
    I'm getting ready to make the run to Abacos next week so had the Cat mechanic go over the engines; I have been down about 150 RPM so didn't want to take any chances. We compared the laser rpm meter to the tachs and all are within comparative range of each other all the way to high idle so that validates the boat's instruments and that I'm in fact down RPM’s at full load.
    He ran a fuel pressure check at the inlet to the rail and found his test gauge was fluctuating
    rapidly between 15 and 30 psi. He should be reading a rock steady 20 to 50 rising with RPM. Then, he connected a clear tube to check for bubbles on the fuel return line - no bubbles thank goodness; that eliminated loose injector seats as a problem. As it ends up there are a series of three small check valves and a spring loaded pressure regulator in the fuel system that if get dirty at all (according to him they all do over time) will not seal and the fuel pump pumping motion will not be dampened which will cause incorrect loading pressure on the injectors and consequently a bad atomization of fuel in the combustion chamber. We pulled oil samples and the soot content was high further indicating a less than ideal fuel burn.
    So he finished the work yesterday and tonight I went to the boat and ran the engines up; let me tell you there is a real difference in throttle response and general engine smoothness; for a simple fix no less….
    Tom

     
    Last edited: Jun 6, 2013
  2. JC3

    JC3 Active Member

    Oct 6, 2006
    Kentucky
    N/A
    N/A
    Tom, Good post. Thanks for posting this. A write up of your trip and pictures of
    the beautifull Bahamas would be nice when you get back :) Good luck, JC
     
  3. HUMPH

    HUMPH Well-Known Member PLATINUM Sponsor

    Nov 4, 2009
    SF BAY AREA
    2003 410DA,
    2004 C14 Caribe
    CAT 3126TA's 350HP/
    50HP Honda
    Interesting, thanks for posting. I would love to know where these check valves and regulators are located.
     
  4. gerryb

    gerryb Well-Known Member TECHNICAL Contributor

    Oct 12, 2006
    Somers Point, NJ
    "On Vacation"
    2006 40 Sundancer
    Raymarine E125 & HD Radar + Garmin 5208
    QSB5.9 380 Cummins
  5. ttmott

    ttmott Well-Known Member GOLD Sponsor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    Yesterday we ran the boat about a total of 6 hours at cruise and occasional full power blips. The boat was around 30% full of fuel and had about 30 gallons of water aboard so rather light. On the pins the tachs indicated 2950 which was great to see; I was impressed with the power delivery and engine smoothness. Also noted was a bit of an algae issue with the fuel so that needs to be corrected before we leave. Regardless, all of the check valves are accessible from outside of the fuel pump. See the attached two pages from the Cat Parts Manual.
    http://i1012.photobucket.com/albums/af244/bumpythecat/SeaRay%20400DA/CatFuelSystem1_zpscde05c7f.jpg
    http://i1012.photobucket.com/albums/af244/bumpythecat/SeaRay%20400DA/CatFuelSystem2_zps9645fcc5.jpg

    Tom
     
  6. JC3

    JC3 Active Member

    Oct 6, 2006
    Kentucky
    N/A
    N/A
    Tom, Please do not forget to get some pictures of the trip! JC
     
  7. ttmott

    ttmott Well-Known Member GOLD Sponsor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    OK, I'll start a thread in the Southeast section.
     

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