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  1. #1
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    Apr 2020
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    Lake of the Ozarks-Osage Beach, MO
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    6

    1999 Mercury 200 EFI starting problems -ECU Pinout

    Hello,

    My husband and I have been working on a motor that has been sitting for a while. I am an automotive technician but these outboards are amazingly complex. We have done the oil delete, replaced all fuel lines, and many other things.
    The problem is that it will start and die within a few seconds. Compression is good. However I just took off the intake and cleaned all injectors and everything inside. We found a small fuel screen that is for the bleed system that was completely clogged. We got the ECU from someone that said was good..... I do not however trust the guy. Would anyone happen to have a pinout of the ECU so I can trace down exactly what wire controls what on the engine? I am very good with wiring and I feel after the oil delete there are a few loose ends that I want to make sure that I know everything about it. I know drivers go bad for the fuel pumps inside them. I dont believe that is the issue. So if anyone has a pinout of the ECU for each wire that would much appreciated!

    Thanks

  2. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Location
    Greenville, SC (US)
    Posts
    94,945
    #2
    Moving your thread to the 2.5L Forum (which is what this engine would be).

    If you would, please take a moment to review the Announcements at the top of the Forum, and be sure to provide the Required Info (serial number) when posting. Thanks!

    The Mercury Service Manual has a limited wiring diagram in the manual, which will help with the specific circuits. Normally, testing is NOT done at the ECU connector, it is done at the individual component (sensors, TPS, Injector Pairs (3), fuel pump, etc). Very simple (Cummins-built) ECU.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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