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  1. #1
    Notorious P.I.G FSHN ROD's Avatar
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    Mar 2006
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    Hillsboro Ohio
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    2,597

    98 225 efi rough idle?

    I have a 98 225 efi all stock . It runs very rough when cold (not AS bad when warm) and smokes like a turned up diesel truck. In a tournament situation when at idle waiting to be sent off and i do get called when i go to take off and punch it it wont do anything but bog down but will eventually start to build rpms and break onto plane where it runs great. Like i said this is only a problem when it is first started or after sitting idle for awhile not as bad after it gets warm. seems like it is getting to much oil. It also is drinkin alot more fuel. Thanks for any help

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  2. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    Apr 2008
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    98,022
    #2

    Re: 98 225 efi rough idle? (ploppin4bass)

    Common causes (certainly not a list of ALL possibilities):

    -Oil system pressure fitting in the crankcase is not releasing pressure from the oil tank properly. To test this, go for a run, shut engine down for 5 minutes. Slowly open the fill cap on the REMOTE OIL TANK, while listening for air pressure to escape. Note: Another common symptom is a "swelled oil tank".

    -Fuel Pump Diaphram leaking.

    -TPI/TPS out of adjustment (see service manual)

    -Temp Sensor malfunction (this can include the IAT sensor as well).



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  3. Kllr bee
    Join Date
    Jun 2004
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    Centerpoint, Alabama
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    1,198
    #3

    Re: 98 225 efi rough idle? (EuropeanAM)

    Try this,when you start the motor don't tilt it all the way down. The hole in the back where the pee hole is needs to be above the waterline. This lets the motor breath and keeps it from loading up. Just before take off tilt her down and let her eat.
    Richard

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