Click for Llebroc Click for United Click for Abeking Click for Mag Bay Click for DeAngelo

Cummins qsm11 problem - solved!

Discussion in 'Technical Discussion' started by Fishy, Dec 24, 2017.

You need to be registered and signed in to view this content.
  1. Fishy

    Fishy New Member

    Joined:
    Dec 30, 2010
    Messages:
    26
    Location:
    global
    The engines are fitted on a 76 Nordhavn and have performed flawlessly for the 2 years I have been onboard, anybody have any theories I would apreciate hearing them, no matter how wild.

    QSM11 350hp 1800rpm 5500hrs 24v
    Boat started and ran with no alarms or indications of problems for 3 hrs coming downriver to get situated for survey and seatrial.
    Right after throttling back to come onto the dock stbd engine dies and won’t start back up.
    Unplugged ecm and plugged back in, engine started and runs at idle at dock.
    Next day both start no problem, haul out, on launch both start up, while backing out of slip port engine dies. Multiple alarms and errors on port.
    Shut down stbd.
    Both engines will turn over and start but as soon as start button is let go, they die.

    Cummins tech plugged into motors and find stbd ecm does not send power to fuel solenoid. Port fuel solenoid measures 21v stbd 0
    Port sends power and all points to engine should start and run but does not.

    New ecm fitted on both and same problem and faults Ecm’s switched port to stbd -same problem and faults Stbd during course of the day blew battery fuse twice but could not get it to blow again.

    Sea fire system bypassed and checked-no effect.
    The plan is to next change out the fuel solenoids but suspect this to be a symptom rather than cause.
  2. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    9,932
    Location:
    Fort Lauderdale
    How old are the batteries? The other fuel solenoid should be getting a lot more than 21 volts.....more like 25.6 volts. I run a Sunseeker with Man common rails and the boat is hard on the group 31 batteries....only 2 per engine......when a battery goes bad.....the Man's will still run, but the engine the bad battery is on will send like 5 erroneous alarms......I'd load test the batteries and check and make sure connections are good (AND GROUND) and the charger is working properly. Battery bank might be bad and living off of charger and charger resets for a minute after you crank the motor and the computers getting low voltage.
  3. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    5,291
    Location:
    Jax FL
    I'm assuming your Cummins tech is spending a lot of time on his phone.
    Skippy J has valid points that should of been looked at when the tech came on board.
    These newer computers, pumps and surrounding relays need juice as far back as DDEC.

    Carbon pile those batteries at the connects to the starters and lightly at the ECM B+ taps to ensure their getting good clean +V juice.
    There is also a 24 to 12Vdc converter in use if your running smart crap (no relation) displays and controls that may lead the can bus a-stray in errors if there is a problem there.

    Keep us up on what is found, were always learning.
  4. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    9,932
    Location:
    Fort Lauderdale
    Also check the gear harness connections as well as all harness connections, but sounds like a ground issue or loose connection on ground.
  5. Fishy

    Fishy New Member

    Joined:
    Dec 30, 2010
    Messages:
    26
    Location:
    global
    Thank you for the replies, I replaced the batteries last December, my guess was also wiring haness/ground issue but the strange thing is of course that it is both engines, even though slightly different symptoms.
    Checked the resistance on fuel pump solenoids, 3 ohm on stbd 1,1 kohm on port.
    I would have thought maybe a lightning strike but no other equiment onboard displaying any symptoms.
    I will post the results when the tech returns in the new year,
  6. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    9,932
    Location:
    Fort Lauderdale
    Does the wiring harness go through the engine controls, seafire system is another one, those are the two systems I can see both engines being wired to. I used to do a lot of engine startups for Cabo. One of them had the CAT guys on board, did the entire seatrial and everything was perfect, pulling up to the dock and went to go to reverse. One engine shut off.......started it up and tried it again, same deal.....forward and neutral it was fine.....it simply was a loose harness connection on the gear.......sometimes it doesn't take much.
  7. Fishy

    Fishy New Member

    Joined:
    Dec 30, 2010
    Messages:
    26
    Location:
    global
    Thats the frustrating part, it could turn out to be a loose connection somewher but so far no luck.
    We bypassed the seafire by “override” and a jumper cable and no change.
    The cummins tech said if it was the seafire the motors would not turn over. That being said seafire is really the only common ground. Metaphorically speaking.
    Engines have now degenrated to just turning over and not firing.

    Merry happy happy, could have been in the bahamas:(
  8. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    5,291
    Location:
    Jax FL
    Sadly, that does not mean anything.
    Check them out and all connects from them to the can-bus (engine harnesses).

    Every station has a box where the engines bus cables are tied together and the displays/clutch7throttle control are tied in.
    Here is where one connect can cause problems for both engines.
  9. Fiammetta42

    Fiammetta42 New Member

    Joined:
    Sep 28, 2017
    Messages:
    15
    Location:
    Cote d Azur
    The 21 v sounds low .
    My 24 v MAN,s bat gauges are usually 28 v +
    For me I would be looking @ the batteries and the connects + earth straps on the engines .
    Do you have a x over switch sometimes called a parallel button .
    Pressing this during starting connects the domestic bank to the dedicated engine bank .If you have this try it to add more juice when attempting to start .
    As well as fuel solenoids requiring a lot of juice the ECM does require a surprising amount too .
    Once the starter motor is running there’s not enough juice to power up the ancillary 21 st century’s stuff that diesels need these days .
    It’s also my understanding that the fuel pump will not squirt below a certain cranking rpm too- again it may be turning over ,but not quite fast enough for a signal to be sent to the fuel pump ,nethermind if it gets a signal ,there’s not enough juice anyhow for it to work properly.
    Last edited: Dec 25, 2017
  10. 30West

    30West Member

    Joined:
    Nov 14, 2016
    Messages:
    248
    Location:
    Holland, Michigan
    If you might be losing voltage somewhere, test the voltage across the battery posts (not clamps), and then across the battery clamps, and then as close to the starter motor connection as possible, all while cranking engine. You should be getting the same voltage under cranking load at all those places, and if not you have found the problem.

    If one of your new batteries has a bad seal around a battery post, that could be slowly creating corrosion under a clamp and not obvious.

    None of this makes obvious sense for both engines to fail, but there are a lot of automatic connections between batteries you might have.
  11. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    9,932
    Location:
    Fort Lauderdale
    I will say it again. It's low voltage. But low voltage across the engine controls, which is causing it to shut down.

    Also make sure the engine controls are not connected to the house bank of batteries and that these batteries are good and not living off of the battery charger.
  12. Fishy

    Fishy New Member

    Joined:
    Dec 30, 2010
    Messages:
    26
    Location:
    global
    Thank you for the replies.
    We changed both fuel solenoids and both engines start and run.
    Cummins tech has no idea why both would fail a day apart, while the engines are now running it does leave me with some aprehension that the cause had been solved.
    Any ideas what would cause both to fail, each motor has its own start batteries.
    Happy 2018!
  13. Capt Ralph

    Capt Ralph Senior Member

    Joined:
    Sep 8, 2004
    Messages:
    5,291
    Location:
    Jax FL
    I remember ordering an electric lift pump for one of two QSCs. After the replacement, when I went to light up the second engine, it's pump was dead.
    Batteries and all were separate.

    It's a reminder that Murphy has a warped sense of humor. I hate that guy...

    Happy & Safe 2018.
  14. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    9,932
    Location:
    Fort Lauderdale
    Check your grounds perhaps. That and the engine controls are common to both engines. Something might be back feeding them. But I don't know. Get a SPARE!!!!!
  15. 30West

    30West Member

    Joined:
    Nov 14, 2016
    Messages:
    248
    Location:
    Holland, Michigan
    Those solenoids were likely manufactured on the same assembly line one after the other. Maybe they had a manufacturing problem that day and both had the same weakness at the same level, and you got lucky.

Share This Page