Click for Walker Click for Burger Click for JetForums Click for Westport Click for Northern Lights

Sunseeker 56 Predator stbd engine won’t crank

Discussion in 'Sunseeker Yacht' started by Marty Medve, Jul 10, 2022.

  1. Marty Medve, Jul 10, 2022
    #1
    Marty Medve

    Marty Medve New Member

    Joined:
    Jul 8, 2022
    Messages:
    7
    Location:
    Pensacola
    Does anyone know what might prevent my stbd engine from cranking?

    28VDC to starter box is good
    IGN switch starts port engine when switched
    Throttle position sensor was jumped so it’s not the problem
    on Pos starts blower and glow plug relay positive

    Man Mechanic says starters never go bad and it’s not clicking either so no solenoid sound.

    bad solenoid could be the answer but it seems like it’s a cutoff instead.

    batteries fully charged as well and power to starter relay is good

    engines are mechanical type vs electronic

    The boat does have a Sea-Fire engine interrupt restart system but I don’t have any idea how it interacts
  2. EShipp, Jul 10, 2022
    #2
    EShipp

    EShipp New Member

    Joined:
    Nov 9, 2013
    Messages:
    15
    Location:
    Kemah Texas
    I had this happen on a Predator 68 MKii

    It was the helm ignition switch. The keyed switch had failed and would not fully turn on the engine management system, so the engine would not start.
    Bought a new switch at the local electronics store to solve the problem . $10 fix.
  3. Marty Medve, Jul 10, 2022
    #3
    Marty Medve

    Marty Medve New Member

    Joined:
    Jul 8, 2022
    Messages:
    7
    Location:
    Pensacola
    Thanks, I’ll try and switch the switches again but I think the engine management system is the problem like you said.
    I switched the wires from left ignition to the right and it did start the left engine

    maybe I should switch the right to the left and see if that works
  4. EShipp, Jul 11, 2022
    #4
    EShipp

    EShipp New Member

    Joined:
    Nov 9, 2013
    Messages:
    15
    Location:
    Kemah Texas
    What engines ? MAN, MTU, or Cats ?
  5. Marty Medve, Jul 11, 2022
    #5
    Marty Medve

    Marty Medve New Member

    Joined:
    Jul 8, 2022
    Messages:
    7
    Location:
    Pensacola
    Man D2848 E403

    non electronic control
  6. mapism, Jul 11, 2022
    #6
    mapism

    mapism Senior Member

    Joined:
    Aug 9, 2008
    Messages:
    2,231
    Location:
    Sardinia
    MM, there's no engine management system on your engines, really.
    The wired black box that you are likely to have on an e/r bulkhead is only a concentrator for routing the probes signals to the instruments, and nothing else. You could even throw it overboard, and the engines will continue to run - just with no working instruments.

    So, even if I understand what your mechanic said about starters never going bad (having never heard of such occurrence myself), it does sound like it happened to yours.
    Anyhow, again, since the engines are 100% mechanical, also for your fire system the one and only way to turn them off is by exciting the stop solenoid.
    Which is something you can also check visually, because it has a pin which is kept pressed inward when the solenoid is excited (=engine off), while an internal spring pops it out automatically when the solenoid is not excited (=engine on). And when it's out, you can also press it manually.
    It isn't very easy to reach it, because it's directly connected to the HP fuel pump, right inside the two cylinder banks, but your MAN mechanic can surely show you exactly where to look.
    Which is important, because if by chance the spring that pulls the solenoid out when not excited is a bit worn out, it can stay pressed as if it were excited, and you'd never be able to start the engine again after turning it off.
    But mind, this is just an aside, because the stop solenoid could be the culprit only if the starter would crank and the engine wouldn't run.
    If the starter doesn't crank and you are sure it's getting a solid 28V supply, I really struggle to think of any reason aside from a blown starter motor.
  7. Marty Medve, Jul 11, 2022
    #7
    Marty Medve

    Marty Medve New Member

    Joined:
    Jul 8, 2022
    Messages:
    7
    Location:
    Pensacola
    Thank YOU SOOOO MUCH

    I’ll try and check what you’ve advised tonight !!
  8. Capt J, Jul 15, 2022
    #8
    Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    14,643
    Location:
    Fort Lauderdale
    Neutral safety switch, look at that. The seafire box could also be stopping it.
  9. Marty Medve, Jul 15, 2022
    #9
    Marty Medve

    Marty Medve New Member

    Joined:
    Jul 8, 2022
    Messages:
    7
    Location:
    Pensacola
    I switched the ign switch but didn’t leave the cutout separate. I’ll try that but I think it’s the starter solenoid.

    intested the Sea-Fire w the tech (good people) and for $500 I’m replacing it anyway.

    thanks everyone!! Likely the starter and I’ll pull it next week. I was hoping it was just a relay or kill switch but doesn’t seem so.
  10. Capt J, Jul 16, 2022
    #10
    Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    14,643
    Location:
    Fort Lauderdale
    Hit the starter several times with a hammer and see if it will then start. If it does, it's the starter.
  11. DOCKMASTER, Jul 16, 2022
    #11
    DOCKMASTER

    DOCKMASTER Senior Member

    Joined:
    Feb 26, 2012
    Messages:
    1,557
    Location:
    Ketchikan, Alaska
    Starter solenoid should be fairly easy to diagnose provided you can access it. Did you try jumping the solenoid with a screwdriver or similar?
  12. Marty Medve, Jul 18, 2022
    #12
    Marty Medve

    Marty Medve New Member

    Joined:
    Jul 8, 2022
    Messages:
    7
    Location:
    Pensacola
    That’s a good idea. Old Navy Pilot Trick! If it doesn’t work, hit it!!

    mill be back on the boat later today and check the last item before pulling the starter. Thanks for everyone’s response. I’ll check the solenoid when I can get to it. Nice that they put it behind the glow plug relay!
  13. Marty Medve, Jul 18, 2022
    #13
    Marty Medve

    Marty Medve New Member

    Joined:
    Jul 8, 2022
    Messages:
    7
    Location:
    Pensacola
    I couldn’t get to it yet without taking apart the starter box. I’ll do that today
  14. mapism, Jul 18, 2022
    #14
    mapism

    mapism Senior Member

    Joined:
    Aug 9, 2008
    Messages:
    2,231
    Location:
    Sardinia
    Glow plug? No such thing to be found, on your engines!