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  1. #1

    Default Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Hi
    boat at dealer who has tried many options
    so the boat fires and starts for approx 1-2 seconds then cuts out, turn the key and starts 1-2 sec then cuts out etc etc
    whats been checked
    batteries 1000 cca
    fuel and tanks on boat and put new fuel tank and fuel from dealer
    air pressure checked
    fuel pressure checked
    changed all spark plugs (after this initial new install it ran longer, turned off but again then would not start.
    engine controls kill cord etc and ignition switch were bypassed so we know it must be the engine only not external
    best weekend weather in the uk for months so not happy
    anyone got any thoughts please

  2. #2

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Since it at least fires - I'd suspect it's starving for gas or too much gas. Try pumping the primer when it starts and see if that helps (i.e. fuel pump/fuel obstruction). Jets WAY off - gets enough gas to start but may be too much to keep it running. Dealer probably tried these but thought I'd try to help.

  3. #3

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Quote Originally Posted by Canufixit View Post
    Since it at least fires - I'd suspect it's starving for gas or too much gas. Try pumping the primer when it starts and see if that helps (i.e. fuel pump/fuel obstruction). Jets WAY off - gets enough gas to start but may be too much to keep it running. Dealer probably tried these but thought I'd try to help.
    DFI and fuel and air pressures all checked out fine.......cheers

  4. #4

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Dealer is getting in a engine brain ? And a crank shaft sensor to try both
    any experts out there

  5. #5
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    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Quote Originally Posted by Bigbuoy01 View Post
    Dealer is getting in a engine brain ? And a crank shaft sensor to try both
    any experts out there
    We are here. This is just a difficult issue to troubleshoot through a keyboard. I would look at the Belt tensioner first....If the belt slips for a half second, the engine will shut down.

    If you loose the 5v reference the engine will shut down

    Get a remote key harness and hook it straight to the engine and retest,.

    If it has smartcraft or any gauges, disconnect them and retest.

    The fuel sender hooked to the 5 volt reference ground can cause many many issues.

    Like I said, hard to diagnose through the keyboard.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  6. #6

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Cheers chris
    dealer tried all those points mentioned.....basically my engine with his fuel tank and controls so it has to be on the engine nothing external. Today Mercury gave him a engine brain ? and the crank sensor to try off another engine and it's not one of these either.

  7. #7
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    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    How did the repair shop check air and fuel pressures? What pressures did they find?
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  8. #8

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Not sure what test equipment used or pressures but confirmed within parameters for this optimax.
    This fault is so consistent I've turn key immediately starts then it's like the key is turned off.....no misfiring etc
    not sure if I can video and attach to this forum but will try tomorrow

  9. #9
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    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Get yourself a couple of cheap fuel pressure gauges and hook them to the air and fuel rails. Start the engine and pay attention to the air. Let me know what you find.

    I shorted direct injector can take the engine down
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  10. #10
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    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    I think you are losing air pressure after cranking and the system is shutting down. How can they tell you everything is within spec if the engine dies after cranking and initial start?

    On an Optimax the direct injectors(air injectors) all go open during cranking to push the air pressure up in the air rail using cylinder compression to close down the fuel regulator to push the fuel pressure up to 90 or 100 psi...

    After the initial start the direct injectors close, the air compressor takes over and the direct injectors cycle with the fuel injectors.

    If the shop where you have your boat at takes off the belt and hooks regulated to 80psi shop air to the air rail and the engine runs your problem is the air compressor...possible bad reeds in the compressor.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  11. #11

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Cheers chris I will get them to try this

  12. #12

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off


  13. #13

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off


  14. #14

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    I've added two videos to show how the engine sounds whilst I try to start it.
    one when I release the key as you would normally and the second keeping the key turned and not releasing

  15. #15
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    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Quote Originally Posted by Bigbuoy01 View Post
    I've added two videos to show how the engine sounds whilst I try to start it.
    one when I release the key as you would normally and the second keeping the key turned and not releasing
    Sounds like you are losing air.

    Their Findings with fuel pressure and are are not correct.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  16. #16

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Does this model have a TPS?

  17. #17
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    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Quote Originally Posted by Bruce2012 View Post
    Does this model have a TPS?

    All Opti's have a TPS.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  18. #18

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Quote Originally Posted by Docksidemarineservices View Post
    All Opti's have a TPS.
    All on hold my end as all the dealers are preparing for the southampton international boat show!

  19. #19
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    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Rig an air compressor to the air rail and test it yourself.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  20. #20

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Hi chris
    sorted !!!
    Barrus engineer attended today and spent 4-5 hours checking through everything and finally found the problem.
    it was a small rubber tube found in the fuel pump area which had broken/ Split and collapsing. Copied in a picture.
    i will look for a drawiing/diagram to identify the said part and let you know.
    i appreciate you taking the time to offer guidance
    Click image for larger version. 

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  21. #21

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Looks like it's item 14 in the diagram, not sure what it does ?Click image for larger version. 

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  22. #22
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    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Did they have the VST tank apart prior to you having the problem? If yes. The damage was done when the tank was put back together. That is how this happens.


    Quote Originally Posted by Bigbuoy01 View Post
    Hi
    boat at dealer who has tried many options
    so the boat fires and starts for approx 1-2 seconds then cuts out, turn the key and starts 1-2 sec then cuts out etc etc
    whats been checked
    batteries 1000 cca
    fuel and tanks on boat and put new fuel tank and fuel from dealer
    air pressure checked
    fuel pressure checked
    changed all spark plugs (after this initial new install it ran longer, turned off but again then would not start.
    engine controls kill cord etc and ignition switch were bypassed so we know it must be the engine only not external
    best weekend weather in the uk for months so not happy
    anyone got any thoughts please
    I guess they did not check the fuel pressure.
    Last edited by Docksidemarineservices; 09-18-2017 at 06:00 PM.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  23. #23

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    No VST has never been apart. New part comes inFriday so will check the pressure question

  24. #24

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Got new seal $32 �� does it fit fully down onto the pump top or sit half on the top pump tube to seal into the housing please Chris

  25. #25
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    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    I would push it into the cover and work the pump into it. Then pull it back apart and check it and do it again. Make sure the rubber does not turn.

    Still curious how the first shop checked your fuel pressure and said it was good.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  26. #26

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    Ok so part fitted today. Engine started and ticked over nicely for 5 mins with 110 psi on the fuel rail (which I see myself) But it cut off! Starts again fine runs between 2-5 mins and cuts off. All the time the rail pressure is held even when it's cut off
    Local dealer been trying all day with Barrus on the phone and still no fix!
    Barrus sending their man over to us again Tuesday with VST

  27. #27
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    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    What is the air pressure at?
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

  28. #28

    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    That was about the same as the fuel around the 100-110 psi Chris

  29. #29
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    Default Re: Mercury optimax 115 2007 Help starts 1-2 secs then cuts off

    It can't be, the air pressure has to be 10 PSI below the fuel pressure.
    Chris
    Dockside Marine Services
    Jersey Shore.
    Mercruiser/Mercury Certified
    Let the insanity begin.

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