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  1. 08-09-2018, 03:45 PM #1
    RCC70
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    91 200 EFI Running bad, need help

    0D136669
    It runs and idles great up to 3000 RPM, then it starts running rough. Boat barely gets on plane and will only run up to 3800 - 4000 RPM's.
    Engine has all done to it in the last 6 months: Fuel lines, bulb, small fuel pump, fuel filter, high pressure fuel pump screen clean, switch boxes, trigger, stator, plugs, fuel pressure 38-40psi,(Injectors and fuel rail cleaned with two injectors replaced by Don) and compression on all cylinders 115-120 psi.
    The stator, trigger and switch boxes were just changed in the last two days since it started running bad?
    Any ideals where to go from here? I do have a factory service manual.
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  2. JOE54
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    #2 08-10-2018, 07:04 AM
    make sure all coils are fireing and all sensors are working (tested),possible ecu problem
    .................................................. ...the scariest thing in life is the unknown ...................................
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  3. EuropeanAM
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    #3 08-10-2018, 08:57 AM
    +1


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  4. RCC70
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    #4 08-11-2018, 09:20 PM
    Ok, I checked spark with tester, two seemed a little weak( 1/2" gap on tester, two were a yellow spark instead of blue) tried a whole coil plate with all 6 known good coils. Still the same results! I'll start with the sensors next, I don't know what I'll do for testing the ECU.
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  5. RCC70
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    #5 08-11-2018, 10:32 PM
    Don or Joe, can the Detonation Control Module be removed on this engine?
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  6. JOE54
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    #6 08-13-2018, 06:56 AM
    sure can just make a jumper (white black wire) on switch boxes
    .................................................. ...the scariest thing in life is the unknown ...................................
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  7. RCC70
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    #7 08-13-2018, 07:56 AM
    And ground the gray wire???
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  8. JOE54
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    #8 08-13-2018, 11:48 AM
    yep
    .................................................. ...the scariest thing in life is the unknown ...................................
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  9. EuropeanAM
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    #9 08-13-2018, 06:16 PM
    I would actually recommend that, if not already done. Notorious for giving problems.

    You MUST perform a Complete Sync-n-Link Procedure (including WOT Timing, especially, and pointer setup with a dial indicator).


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
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  10. RCC70
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    #10 08-13-2018, 08:24 PM
    OK update, Thank you you so much Joe & Don for pointing me towards the sensors again. After going nucking futs with this this and started from square one in the manual AGAIN. Found the supposed," like new switch box "( I know Mr Don, it was a CDI and not OEM boxes) out of spec on the bias circuit!
    Also, thanks to my local dealer( Also a Don) for the slightly used parts to try! Now I have to replace my old stator and trigger with the borrowed ones.
    Neadless to say, it's running like a spotted ^ss ape now. It's never ran this good in the 4 years I've had it!!!!
    When I swap out my original stator and trigger with the borrowed ones, I plan on removing it after I slowly replace my original stator and trigger.
    Thanks again!
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  11. RCC70
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    #11 08-13-2018, 08:29 PM
    This was about the 3rd link-n-sync I've done on it covering all my bases on it. Using a dial caliber instead of a indicator with the tools I have available to me.
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  12. RCC70
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    #12 08-13-2018, 08:38 PM
    Don I think (95%) my WOT timing was off since I've had this boat. The secondary butterflies (top) only was opening 2/3rds of the way of WOT ( what I thought was WOT). Other than the bad switch box.
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  13. RCC70
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    #13 08-13-2018, 08:54 PM
    I know I should probably leave/pay for the slightly used stator/trigger on this engine, but it is for sale. An the price is kinda steap for me at this time. I understand the old stator and trigger could last 2 hours, days, months or years. I will swap back to my stator and trigger for sure.
    Thanks again Don and Joe!!!
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  14. JOE54
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    #14 08-14-2018, 06:49 AM
    .................................................. ...the scariest thing in life is the unknown ...................................
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  15. EuropeanAM
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    #15 08-14-2018, 09:53 AM


    One note: Switchboxes really should be replaced IN PAIRS, as the bias circuitry is often damage in what is perceived to be the "good" box.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
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