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  1. #1
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    2000 Optimax 225 bogging down - Need some help!

    Hey Guys, I have a 2000 225HP Optimax Ser # 0G839677 that is running like crap under way / load. It starts, idles and revs perfect but in the water it starts breaking up / surging at around 1200, wont really accelerate unless I floor it then the engine will surge a few times and then accel hard to near 3K, when it hits 3k its not sounding like its on a rev limiter but more like the engine is maxed out, I have the throttle all the way open but thats all it has, it will run 3K for a second than drop to 2500, then slowly bog it self down over a several minutes running worse and worse even with leaving the throttle at WOT. I used to work on cars for a living, if this was a car I would suspect the timing or fueling curves are off but I not familiar enough with optis yet to know how what affects what


    So far I have done...


    Replaced all filters
    Opened the VST - looked clean, no debris or fuel hose bits
    Checked pressures - I got 92 fuel, 82 air, 6-ish low pressure
    I checked spark with a gap tester and it jumps 3/8 in no problem on all 6
    I pulled the injector connectors one by one and each made the engine run rougher so all 6 are firing
    Pulled the low pressure pump connector and low pressure PSI dropped from 6PSI to 0
    Rebuilt the pulse pump on the side of the block
    Pulled the high pressure pump connector and it instantly stopped running
    Compression cold is 90ish on all 6, my understanding is doing the special optimax method will yield 20% higher
    Plugs not fouled but noted each one had a little bit of wet oil on them, probably from incomplete burn. Replaced end of last year, minimal hours on them.
    Tracker and diaphragm both replaced last year
    Ran on a 3 Gal tank with a half bottle of quickleen


    I have no beeps at this time, I know I need to get the codes scanned... I still need to find a decent shop that knows optimax, what should I ask for from them? I talked to one shop and he said all they know how to do is read hard faults, if something has a hard fault it will beep right?

    At this time I am trying to self diag and I like having spare parts for common failure items, I had a spare inside TPS, it made no difference, was thinking about ordering an outside TPS, the thing that goes in-between and a crank sensor aka "enoder" to try next. I have seen failing crank sensors on cars kill the mid range and the reason for TPS is I find it odd that it will sputter and surge if I WOT and then jump to 3K like its all good before it starts bogging down again.

    Any ideas of what else to check / replace?

    Here is a video of it surging with gauges, the air is kinda hard to see but its holding 80, the low pressure is bouncing from 5 to 8, I am suspecting its from the float opening and closing but it could be the gauge is too big to accurately read it. If I hold WOT and let it stutter to 3K the pressures all stay the same... https://streamable.com/3zjz5x

  2. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #2
    Really need to get it on an appropriate diagnostic tool and get printouts.

    Shift switch working properly?


    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).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  3. Member
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    #3
    Quote Originally Posted by EuropeanAM View Post
    Really need to get it on an appropriate diagnostic tool and get printouts.
    When I call around what should I ask for? Faults and printouts of the last hour of runtime?

    Quote Originally Posted by EuropeanAM View Post
    Shift switch working properly?
    I think so, its shifts in and out of gear without grinding or noise. Are these the motors that disrupt the spark when shifting in and out of gear?

  4. Member Bob G.'s Avatar
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    #4
    The diagnostics printouts will include the run history, freeze frame (fault) history and fault seconds counter. It will have all of the info since the motor was new unless it was cleared out by a someone with a diagnostic tool.
    2006 Triton TR-21 XD, Mercury 225 Pro XS, S/N 1B287870

  5. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #5
    +1.... and the shift switch simply signals the PCM that the engine is in gear or in neutral, as well as letting it know there is a change occurring from one to the other.


    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).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  6. Member
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    #6
    I have been having trouble getting a shop to look at the old Opti so I bought a DDT off <ANNOUNCEMENTS> so I could do my own diagnostics, gonna test it out this week. Are there any guides on how to use it anywhere or is it pretty straight forward?
    Last edited by EuropeanAM; 08-28-2023 at 07:27 PM. Reason: Please read Forum Announcements

  7. Member
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    #7
    which chip you get ????? 5.0 hopefully
    .................................................. ...the scariest thing in life is the unknown ...................................

  8. Member
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    #8
    5.0 and DDT is fairly easy to use except the print out- you need some sort of ancient printer port to use it. The first enlightening thing I found out is my motor is not limiting at 3K.. my tach is. SO my new issue is my motor surges and runs like crap between 1500 and 4000 rpm? At WOT it runs decent. All the tests pass and there are a bunch of faults but I think they are from me messing with stuff. I documented the faults and I guess I need to take it out and see if there are any new ones. Any thoughts?

  9. Member
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    #9
    clear all faults and then go run it see if new ones occur. pay close attn to TPS , and MAP functions
    .................................................. ...the scariest thing in life is the unknown ...................................