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  1. #1
    Tbender
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    Merc 250 Optimax Pro XS Problem

    Yesterday I decided to blow out the cobwebs on my motor and opened it up, planned to let it go for a couple of minutes. After about 1/4 mile at full rpms it was like it the motor just lost rpms and would run only at about 5000 rpms. It didn't run rough, but if I tried to accelerate it was like I hit a rev limiter........nothing. So I came in, checked my fuel filter and opened the water drain (which no water drained out). So, this morning I took it out for another run. After warming it up, I opened it up for about a mile, and it felt normal. I fished for about an hour, then took off again at full throttle and after 200 yards the same thing that happened yesterday occurred. This motor is a 2009 model and since I've had it the high stage fuel pump has been replaced twice. The dealer/mechanic never found the cause of the fuel pump failure. I sure would appreciate any help anyone can give..............Thanks

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  3. Mercury - 3 Liter Moderator EuropeanAM's Avatar
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    #2
    Can you provide the engine's serial number?

    One thing I would recommend.... if you can replicate the "low power" situation, and have a TIMING LIGHT, try clipping the inductive pickup to one plug wire at a time (watch for the light to flash).

    If any one wire is found to not be producing spark.... get it in to your local dealer (and have them reference SB 2009-026).


    Dual Mercury Master Technician- for Mercury Outboards, Racing & Mercruiser Sterndrives in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 38 years (learn something new every day).
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  4. Tbender
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    #3
    Don, the serial number is 1B722969.

  5. Mercury - 3 Liter Moderator EuropeanAM's Avatar
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    #4
    Quote Originally Posted by Tbender View Post
    Don, the serial number is 1B722969.
    Definitely check spark as above suggested (or better yet, have an Authorized Mercury Dealer do it via an "Auto Self Test- Plugs OUT of Cylinder Head while connected to the Computer Diagnostic System).

    Refer them to SB 2009-026 if spark is not present on any plug wire.


    Dual Mercury Master Technician- for Mercury Outboards, Racing & Mercruiser Sterndrives in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 38 years (learn something new every day).
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  6. Tbender
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    #5
    Don, I took it to my dealer this morning.........the mechanic did the spark plug test as you described.....all normal. He did other tests and all turned out normal. He thought that the problem was an ignition coil and gave me a new one to start replacing one of my coils at a time and checking to see of one of them is the culprit. Since I live right on Toledo Bend, I did all that today and all of my coils performed the same......after about a mile at top speed and about 6000 rpms, it was like the rev limiter kicked in. I called and told my dealer the results and I think he seemed to think I have a faulty rev limiter. I'll know tomorrow after he researches rev limiter problems.

    By the way, this is the same engine that would lose rpms when I used the trim or hydraulic jack plate and was a dog out of the hole.....also would only run 4500 rpms. That was solved when the high stage fuel pump was replaced.

  7. Mercury - 3 Liter Moderator EuropeanAM's Avatar
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    #6
    If it does this again, take VERY CRITICAL NOTE of the RPM's it drops to.

    This is important... as there's a substantial difference in potential "causes" based on the actual RPM's lost.

    Example: 6000 beginning, dropped to 5000 is an indication that you may have lost one cylinder, whereas 6000 beginning, and slowly dropping down to 5600-5800 could be something totally different (in that case, give me a call).


    Dual Mercury Master Technician- for Mercury Outboards, Racing & Mercruiser Sterndrives in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 38 years (learn something new every day).
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  8. Tbender
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    #7
    Yesterday, I made 6 WOT runs, each after I replaced each coils with the new one. After each run, when I reached about 6000 rpms, the rpms dropped slowly as you described, then I went to idle, turned around, then made another run at WOT and the same thing happened, only sooner than the first time. This happened on all six runs. Also if I continued my run after the rpms dropped, the engine ran normally, only up to about 5000 rpms with no throttle response if I accellerated when at 5000 rpms. When I say it ran normally, there was no miss, and throttle response was normal at any speed up to 5000 rpms. On all the runs, my top speed was normal (about 72 mph) before the rpms began lowering. My hole shot was also normal.

    I believe that had I not made a WOT run the first time (about 5 days ago) I would have never known I had a problem. I usually cruise at about 4000-4500 rpms. Rarely do I run at top speed.

    Thank you very much for your responses to my problems..........greatly appreciated.

  9. Mercury - 3 Liter Moderator EuropeanAM's Avatar
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    #8
    Was nice talking with you today.

    If you get the chance, drop me an email with the engine serial number and a PICTURE of the PCM (showing all tags/decals).

    I'll see if there may be something there that can help your "guy".


    Dual Mercury Master Technician- for Mercury Outboards, Racing & Mercruiser Sterndrives in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 38 years (learn something new every day).
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  10. Tbender
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    #9
    Don, the S/N is 1B722969. Upper sticker info on PCM: 8M8022142, 828008 06, Racing 250HP 3.0L OPTI.

    Lower sticker info: XR002V0B, PCM0701, 9-28-2008. The pics I took turned out terrible....poor resolution and focus.

  11. Mercury - 3 Liter Moderator EuropeanAM's Avatar
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    #10
    This calibration should not be causing the problems you're experiencing.

    I'm going to suggest the following (you will need to enlist your dealer's assistance):

    -PRINTOUTS of the Run History, and Freeze Frame (Fault) History. I'll be glad to review them by email.

    -Test Run on the water, with Computer Diagnostic System Connected. While running:

    (1): Perform a DATA RECORDING of the engine while RPM's are dropping at WOT.
    (2): Perform a CYL MISFIRE TEST of the engine while RPM's are dropping, and note RPM loss with each cylinder.

    (one of the two above items will very likely narrow down the problem to a specific item, or list of items).


    Dual Mercury Master Technician- for Mercury Outboards, Racing & Mercruiser Sterndrives in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 38 years (learn something new every day).
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  12. Member
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    #11
    Took my boat out today after working on it it had a miss and losing rpm now the miss is gone it want run but 74 it did run 79

  13. Mercury - 3 Liter Moderator EuropeanAM's Avatar
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    #12
    Quote Originally Posted by jmoore2 View Post
    Took my boat out today after working on it it had a miss and losing rpm now the miss is gone it want run but 74 it did run 79
    Welcome to BBC!

    If you would, please open your own topic/thread for questions on your engine (and provide complete information or details- especially the engine serial number).

    Thanks!


    Dual Mercury Master Technician- for Mercury Outboards, Racing & Mercruiser Sterndrives in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 38 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor