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  1. #1
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    225 Opti erratic idle

    Model OPti 225L, S/N 0T944253

    The idle speed began jumping all over the place today. It will surge to 2500 or more, drop, bounce around and then go back to normal operation.
    During this, the Smartcraft Gauge says "Engine Data Bus" or something like that.
    Did a search, similar symptoms, seems the TPS may the culprit.

    thanks in advance

    C
    Last edited by rangercj; 07-04-2021 at 08:32 AM.

  2. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #2
    Do you have a fuel/oil/paddle harness on this engine/boat? If so: UNPLUG IT COMPLETELY at the engine, and see if the problem persists.


    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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  3. Member
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    #3
    If this is the plug for the fuel/oil/paddle harness ( I hope), then no.
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    Last edited by rangercj; 07-04-2021 at 12:46 PM.

  4. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #4
    We can rule that out, then. Likely either a faulty TPS, OR some other 5V sensor that is erratic/failing/failed within range.


    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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  5. Member
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    #5
    TPS ordered. Are there any tricks to removing/replacing the TPS ?

    I will post the results when done.

    Thanks again and again and again...

  6. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #6
    Strongly recommend the TPS, Lever, and cover all be replaced at the same time. Simply install the lever (it fits quite snug into the TPS), assemble onto the engine bracket, connect the link arm by squeezing the ball and socket together (fingers or pliers).

    Turn key on, start and should be good.


    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

  7. Member
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    #7
    Unfortunately, this did not fix the problem. The idle isn't so much erratic as it is just high. It climbs from 900 or so to 1800-2200 over 30 seconds after starting. It
    is the same with either TPS. Also smells of gas. Fuels systems on these are out of my league. It's off to the mechanic.

    thx again

  8. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #8
    Going to need to get someone to check it for "excess, unmetered fuel" getting into the engine. This can be due to a pulse pump diaphragm leak, tracker valve, fuel pressure or air pressure regulator diaphragm, leaking injector o-rings, any air leak, water in fuel sensor leaking into the cowling, etc.


    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

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    #9
    We have a winner. The remains of the "water in fuel" sensor. It pulled right out of the black fitting while being removed. There was a lot of "unmetered" gas pouring into the cowling. Parts on order...
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    #10
    yea they dont like that raw fuel in there
    .................................................. ...the scariest thing in life is the unknown ...................................

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    #11
    This is what we did at the shop...

    Hooked up to gauges and computer, hood off, started up. Idling fast but slower than with hood on (makes sense I think).
    Mechanic said the air and fuel pressures were good. Then we saw the gas pouring from the sensor and shut it off.
    I think it went from leak to complete failure while he was testing it.

    Sensor replaced, no leaks, no smell. However it is still idling high, around 950.

    The replacement TPS, arm and cover are still in there and I have not adjusted any of the linkages.

    Is it likely that the new TPS would cause it to idle a couple hundred rpm high?

    Plan is to put the orig TPS back and check all the linkage clearances, then go test.
    Last edited by rangercj; 07-18-2021 at 11:30 AM. Reason: add info

  12. Member
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    #12
    Original TPS installed, idles at 600. Went for a short drive, all OK to 5k rpm. (My 04 TR20X flat out flies with this motor, always has) Hopefully I'm done working on it and can go fishing in it.

    You guys rock, thx
    C

  13. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #13


    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