Diaganostic Help

Discussion in 'Gas Engines/Drives/Transmissions/Props' started by SeaRenity, Feb 14, 2018.

  1. SeaRenity

    SeaRenity Member

    158
    Mar 31, 2008
    chesapeake bay / Back river
    320 Sundancer 2005
    350 Mag hor.
    As you can see by my signature I have 350 Mag horizons, which the starboard engine for the last year has shown some changes. I noticed it takes more throttle (than port) to get to the desired RPM ( usually run 3800 or so) this engine also seems o burn more fuel ( port 12.6 gph vs 13.5 for engine in question.
    I've read here that possible fuel injectors could be the problem. Need help with determining if it is injector problem -- how do I know and is there something I can do.
    I always run Star-tron with my gas and I am forced to use E10. Any help???
    Thanks
    Rich
     
  2. superwa

    superwa Member

    55
    Jul 27, 2013
    Rhode Island
    2001 Sea Ray Sundancer 380
    Mercruiser horizon 8.1S
    Have you tried something that will clean the injectors a little more? Maybe sea foam? Also, is that the difference for just the engines or you also run a generator from that tank.
     
  3. Stee6043

    Stee6043 Well-Known Member

    Jun 1, 2015
    West Michigan
    1997 Sundancer 400
    Past:
    1999 Sundancer 340
    7.4L Gassers
    I'd check to make sure it's not something more obvious before diving in on internal engine components. Are your throttle cables still 100% free and adjusted correctly? They can creep/stretch over time (at least mine have). If your boat is out of the water you may also want to make sure something hasn't happened to your running gear. Arrestors both clean? Trans oil fresh, both sides?
     
  4. SeaRenity

    SeaRenity Member

    158
    Mar 31, 2008
    chesapeake bay / Back river
    320 Sundancer 2005
    350 Mag hor.
    Thanks for the responses, I ruled out throttle cable because along with increased throttle I have noticed higher than usual fuel usage. I do not have a generator so, this is not the culprit and it would not effect gph while running. Boat is on the hard and running gear appears fine. Tranny fluid has been replaced recently and new plugs, rotor, cap and wires have been installed on starboard engine
     
  5. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    You can run a fuel pressure gauge, but it only tells you what is feeding the injectors - it won't tell you what the injectors are actually doing. Injectors can be cleaned for about $20 each and there are worse things to do - worst case, it's good PM for the future. I do think it would be a good idea to run the fuel pressure gauge, though - just to help narrow things down as you're in the era of the CF paint problems.
     
    Last edited: Feb 14, 2018
  6. Korkie

    Korkie Member

    152
    Feb 2, 2016
    Breton Bay, MD
    2006 Sundancer 340, Garmin 7612, HDx Radome
    Merc 496 Mags, Bravo III Drives
    SeaRenity, Had same issue. Powering up you have more throttle than the motor gives you rpms. My mechanic diagnosed mine by ruling out the fuel pumps, took out and bench tested flow, filter - replaced, plugs - replaced. After all this he sprayed fluid straight down the air intake and the motor ran smoother. This bypasses the injectors. Removed injectors and sent away. After re install, sea trialed boat with him. max rpms before was 3200, now max is 4450. And what a huge difference in power getting up on plane. I did the other motor myself with the assistance of a friend for about 1 third the cost of the marina. I sent my injectors out to:
    They clean them to original specs. Check out their web site. Only takes about a week.
    Best thing I did in regards to performance and power. At WOT, I used to get up to about 35 - 36 mph, after the cleaning I can run 44 with good sea conditions and a light load.
    Unless you are familiar with doing this, enlist the assistance of someone who is.
     
    villain style likes this.
  7. CliffA

    CliffA Well-Known Member GOLD Sponsor

    Dec 29, 2009
    Lake Norman, NC
    2001 Sea Ray 340DA
    Name: 'Happy Place'
    4.5kW West. Generator
    Purchased Nov. 2014
    Fresh Water Use
    Twin Merc. 6.2L (MPI)
    Raw Water Cooled
    V-Drive Transmissions
    upload_2018-2-14_16-18-30.png
    +++++++++++++++++++++++++++

    actually this supplements the injectors with extra fuel....the fact that the engine started running smoother when fuel was shot into the air intake told the mechanic the injectors were not supplying enough fuel.....most likely because they were dirty and partially clogged.....

    cliff
     
    Last edited: Feb 15, 2018
  8. Espos4

    Espos4 Active Member

    384
    Jan 1, 2017
    Long Island NY
    2007 240 Sundeck
    350 MAG Bravo 3 W/DTS
    Judging by your year (2005) I assume you have Cool Fuel 3.

    If you haven't had them replaced, and you're concerned about the internal paint issue, you can put a fuel pressure gauge on the motor(s) to possibly diagnose and issue.

    If you see noticeably higher fuel pressure, that is a symptom of paint fouling the fuel system.

    43 psi is the spec for my 2007, it was over 55psi according to the work order when it was diagnosed as needing the new CF3 module a few years ago.
     
  9. SeaRenity

    SeaRenity Member

    158
    Mar 31, 2008
    chesapeake bay / Back river
    320 Sundancer 2005
    350 Mag hor.
    Thanks for all the help. I do have CF3 and I have had relay issue and somewhat burnt connectors on the relay which might tell me I have a high draw from increased fuel pressure?? Does the interior paint on the CF3 clog the injectors or just contaminate the fuel filters??
     
  10. Espos4

    Espos4 Active Member

    384
    Jan 1, 2017
    Long Island NY
    2007 240 Sundeck
    350 MAG Bravo 3 W/DTS
    The filters generally aren't affected, as they are placed before the area where the paint delaminates. The paint moves down the line and affects the fuel pressure regulator and the injectors.

    FYI, there are 2 fuel pressure regulators on the CF3 engines. One is on the fuel rail on top of the intake manifold, this one isn't used, its essentially a Dummy. The "real" fuel pressure regulator is mounted on the CF3 module. You'll see a small vacuum hose attached to it. If you remove this one, you may be able to see paint chips and debris if in fact you have a "CF3 paint issue"
     
  11. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    You should have a Merc shop look at it - if it is due to the paint issues, there's a possibility that Merc will cover the repair. It seems to be on a case-by-case basis and somewhat determined by how the Merc shop presents it to Merc.
     
  12. villain style

    villain style Active Member SILVER Sponsor

    Oct 10, 2006
    Mears Point Marina Kent Island, MD
    2006 44 DA
    QSC 8,3s
    Cummins QSC 8.3s 500HO
    Hi, first your boat is beautiful. Have a question - How long and how big a job is it to remove fuel injectors...
     
  13. Bt Doctur

    Bt Doctur Well-Known Member

    Aug 21, 2010
    New Jersey
    Ex SRV 240 Weekender twin
    in between
    depending on your engine and what needs to be removed first about 2 hours
     
    villain style likes this.
  14. villain style

    villain style Active Member SILVER Sponsor

    Oct 10, 2006
    Mears Point Marina Kent Island, MD
    2006 44 DA
    QSC 8,3s
    Cummins QSC 8.3s 500HO
    Thanks - And I have 2006 8.1"S
     
  15. SeaRenity

    SeaRenity Member

    158
    Mar 31, 2008
    chesapeake bay / Back river
    320 Sundancer 2005
    350 Mag hor.
    Is there any way to know a specific fuel injector that needs cleaned? Or do all need to be removed and cleaned?
     
  16. Espos4

    Espos4 Active Member

    384
    Jan 1, 2017
    Long Island NY
    2007 240 Sundeck
    350 MAG Bravo 3 W/DTS
    If you suspect a clogged injector or you confirmed that there is indeed paint debris in the fuel system, it may be difficult to pinpoint which injectors are affected, they may all have debris in them. A good mechanic with the proper computer diagnostic tools could be a help, but his cost could be more than the money saved by cleaning say, 4 injectors vs. 8 if that was the case. (Looks like you are attempting to do this yourself)

    If you suspect a clogged injector or you confirmed that there is indeed paint debris in the fuel system, then i would recommend having them all cleaned or replaced. You will also need to flush the fuel line from the CF3 module up to and including the injector rails.
     
  17. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor GOLD Sponsor

    Apr 21, 2009
    PA
    Various
    Various
    Clean them all. It only costs about $20 each and, at the very least, it's good PM. Have you talked to a Merc shop as I suggested above?
     

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