Cleaning fuel injectors on 8.1's- should I or shouldn't I?

Discussion in 'Gas Engines/Drives/Transmissions/Props' started by amajamar, Jan 9, 2020.

  1. amajamar

    amajamar Active Member

    167
    Sep 9, 2013
    Onset, MA
    2001 380 Sundancer
    8.1S Horizons
    I have a 380 dancer with about 500 hours on 8.1's. They run very well, but I do notice some black exhaust "soot", which accumulates around the above-water exhaust ports. Sometimes at idle they smell like they are running rich, too. Oil testing shows no fuel residue. I'm wondering what other people's experience having injectors cleaned has been. Do you think that this would help the sooty exhaust issue? Do you find that having the injectors cleaned has saved you any fuel? Again, she runs great, so not noticing any performance issues. Looking forward to your thoughts.

    Thanks in advance!
     
  2. Ididntdoit

    Ididntdoit Well-Known Member

    Dec 5, 2007
    New England & South Florida
    Boatless
    Boatless
    is your fuel pressure in spec? if no other symptoms, i would treat a couple tanks with techron
     
  3. amajamar

    amajamar Active Member

    167
    Sep 9, 2013
    Onset, MA
    2001 380 Sundancer
    8.1S Horizons
    Yes, fuel pressure is normal. Can the techron make a difference?
     
  4. RBB

    RBB Member

    76
    Dec 18, 2019
    Kentucky
    2004 390 MY
    8.1’s
    If it’s running fine and everything else seems fine I wouldn’t do anything.
     
  5. amajamar

    amajamar Active Member

    167
    Sep 9, 2013
    Onset, MA
    2001 380 Sundancer
    8.1S Horizons
    Do you get sooty exhaust with your 8.1's?
     
  6. Jimmy Buoy

    Jimmy Buoy Well-Known Member

    Dec 3, 2008
    Sarnia, Ontario, Canada
    340 Amberjack
    twin 8.1S 370 Hp + 4.5 Westerbeke Genset
    Mine run great as well and they have always accumulated black soot around the top of the large thru-hull exhaust ports. I usually have to give them a quick wipe with cleaner upon returning. I run 4500RPM WOT which is on the low end of the specs, but the engine doesn't seem to lug at any RPM and do most of my cruising at 3600RPM. Maybe too much prop load??

    When first started, the engine does have a rich smell, but she runs just fine. I'm from the school of "if it aint broke - don't fix it" so I personally wouldn't be messing with injectors at this point.
     
    RBB likes this.
  7. sbw1

    sbw1 Well-Known Member

    Oct 10, 2006
    West Michigan
    This is listed in my signature
    This is listed in my signature
    IMG_4230.JPG I put about 1000 hours on my 8.1s and never did anything to them except run high quality fuel without ethanol in them, change the oil, impellers, the spark plugs and coolant twice. Both turned the same wot RPMs as when brand new when we sold the boat after 15 great years of boating. Use good fuel and oil and follow the maintenance schedule in your owner manual.
     
    RBB likes this.
  8. RBB

    RBB Member

    76
    Dec 18, 2019
    Kentucky
    2004 390 MY
    8.1’s
    Maybe a little, but I learned along time ago not to fix what’s not broke. U said they run fine , no trace of fuel in oil.
    Are u idling a lot? Run it and enjoy it.
     
  9. amajamar

    amajamar Active Member

    167
    Sep 9, 2013
    Onset, MA
    2001 380 Sundancer
    8.1S Horizons
    Sounds like good advice, especially if other 8.1's run a little sooty too.
     
  10. Spark600

    Spark600 Member

    90
    Dec 28, 2013
    Long Island NY
    2008 Sundancer with 496 SeaCore Bravo 3
    Kohler Generator
    Mercury dinghy
    496 SeaCore Bravo 3
    When talking to MerCruiser about the engines running rich ( Smell Gas ) they said they make them run rich to cool the pistons with the gas.
     
  11. amajamar

    amajamar Active Member

    167
    Sep 9, 2013
    Onset, MA
    2001 380 Sundancer
    8.1S Horizons
    Well, it's certainly better than running lean and burning a piston, I suppose...
     
  12. paulswagelock

    paulswagelock Well-Known Member

    Oct 25, 2010
    pa
    2018 SDX 270 OB 300 Verado
    Verado 300
    I changed them on my last boat with the 8.1. They were 7 years old and 300 hours and I found the manufacturer set for $349 new. Friend had same engine/yr/hours and developed problems with 2 injectors so I went at it proactively. I had the old set tested and rebuilt, and they were not too bad, within ~15% of spec.
    I noticed a little smoother idle, but nothing else really changed.
    The job isn't that hard, but in hind site I would not have done it based on the minimal improvement, and just waited until I had a problem.

    http://clubsearay.com/index.php?thr...injectors-merc-8-1-496-mag.84986/#post-956142
     
    Last edited: Jan 10, 2020
  13. amajamar

    amajamar Active Member

    167
    Sep 9, 2013
    Onset, MA
    2001 380 Sundancer
    8.1S Horizons
    This is good to know. BTW, where did you find OEM injector set for 349? Sounds to good to be true!
     
  14. paulswagelock

    paulswagelock Well-Known Member

    Oct 25, 2010
    pa
    2018 SDX 270 OB 300 Verado
    Verado 300
    At the time, from Michigan Motorz.
     
    amajamar likes this.
  15. Pilot

    Pilot Member

    209
    May 7, 2009
    Chesapeake Bay
    2009 370 Searay DA
    V Drives
    Twin 8.1's
    I did mine with seafoam. Just running the tanks pretty low on fuel the invest in a few bottles, enough to really douse it. Makes them run great and cleans and acts as a preventative as well.
     
    Jimmy Buoy likes this.

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