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  1. #1
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    1998 3.0l 225 EFI Project Performance Questions

    Hey all,

    Just got my 225 EFI all put back together. This is my first time building one of these motors and I have a couple (maybe noob) questions.

    Here's what's done to the motor:
    300 PM Ignition ECU - 830044 6
    250XB Fuel Ecu - 830046 15
    300 PM 60cc heads w/ 125 psi compression across all 6
    4 butterfly intake
    Chris Carson race reeds

    1. Where should my TPS be set for idle and WOT. It is currently at 1.02 idle and 3.95 WOT The motor is idling alright, but occasionally hesitating to start at first and smoking a lot. I just want to make sure I'm not lean anywhere.
    2. Are there any other adjustments that need to be made to have this motor operate properly?
    3. Is 125 psi compression enough to get the benefit of 93? And should I pump what's left in the tank and change it out for 93?

    I have yet to get it on the water, just idling on muffs. Any other pointers would be great!

    Thanks
    -Andy
    2002 Stratos 20XL w/ 1998 Mercury 225 EFI

  2. #2
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    Quote Originally Posted by xringmaster View Post
    Hey all,

    Just got my 225 EFI all put back together. This is my first time building one of these motors and I have a couple (maybe noob) questions.

    Here's what's done to the motor:
    300 PM Ignition ECU - 830044 6
    250XB Fuel Ecu - 830046 15
    300 PM 60cc heads w/ 125 psi compression across all 6
    4 butterfly intake
    Chris Carson race reeds

    1. Where should my TPS be set for idle and WOT. It is currently at 1.02 idle and 3.95 WOT The motor is idling alright, but occasionally hesitating to start at first and smoking a lot. I just want to make sure I'm not lean anywhere.
    2. Are there any other adjustments that need to be made to have this motor operate properly?
    3. Is 125 psi compression enough to get the benefit of 93? And should I pump what's left in the tank and change it out for 93?

    I have yet to get it on the water, just idling on muffs. Any other pointers would be great!

    Thanks
    -Andy
    .95 to 1 is good on the tps. Really the only adj. you can make there. Make sure your stator is good. Really a weak point on this motor. Ohm it out. Did you check out the lift pump? Torn diaphram will leak fuel in the motor and run real rich.Use 93 if possible,if fuel is old regular,get rid of it. These engines smoke alot when first started. Good luck.

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  4. #3
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    If you're lean...it will spit and sputter occasionally at idle...known as lean sneeze.

    3.0 love compression. If you have a good supply of 93 octane in your area, have some heads cut to 140 PSI. With the other mods you have done, it will really wake that motor up.
    "We, the unwilling, led by the unknowing, are doing the impossible for the ungrateful. We have done so much, for so long, with so little, we are now qualified to do anything with nothing."

  5. #4
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    Quote Originally Posted by bsumner View Post
    If you're lean...it will spit and sputter occasionally at idle...known as lean sneeze.
    I know all about lean sneezing. I am more concerned with being lean at WOT.

    Quote Originally Posted by bsumner View Post
    3.0 love compression. If you have a good supply of 93 octane in your area, have some heads cut to 140 PSI. With the other mods you have done, it will really wake that motor up.
    Do I currently have enough compression to benefit from 93? Should I be worried running 87 with my current set up?
    2002 Stratos 20XL w/ 1998 Mercury 225 EFI

  6. #5
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    tps setting is fine. what oil mixture are you running on the first start up and break in? i would be using 93 if i was you. with new fuel.
    Check what fuel pressure are you running?
    Whats your ign timing?
    Whats your squish band measure ment to?
    What spark plugs are you running?

  7. #6
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    Quote Originally Posted by xringmaster View Post
    I know all about lean sneezing. I am more concerned with being lean at WOT.

    Only way to know is to make a full throttle run and cut the key. Pull plugs and read the top of the pistons for burn pattern.



    Do I currently have enough compression to benefit from 93? Should I be worried running 87 with my current set up?
    You need to run 91 octane minimum and 93 if you have it.
    "We, the unwilling, led by the unknowing, are doing the impossible for the ungrateful. We have done so much, for so long, with so little, we are now qualified to do anything with nothing."

  8. #7
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    Quote Originally Posted by R.grover View Post
    tps setting is fine. i would be using 93 if i was you. with new fuel.
    Alright thanks, will probably get rid of the 87 in the tank and refill with fresh 93.

    Quote Originally Posted by R.grover View Post
    What oil mixture are you running on the first start up and break in?
    I've ran the motor for 15 mins on 50:1, and that's all the time it's run currently. Please let me know if this is incorrect.

    Quote Originally Posted by R.grover View Post
    Check what fuel pressure are you running?
    ~35 psi

    Quote Originally Posted by R.grover View Post
    Whats your ign timing?
    I have not messed with it, it's timed per the service manual.

    Quote Originally Posted by R.grover View Post
    Whats your squish band measurement to?
    I didn't actually take a measurement, but the heads are off a 300 PM and I would assume that this isn't an issue.

    Quote Originally Posted by R.grover View Post
    What spark plugs are you running?
    Don't remember the exact part number, but the champions per the service manual.

    Quote Originally Posted by bsumner View Post
    You need to run 91 octane minimum and 93 if you have it.
    Alright thanks, probably going to drain the 87 and refill with 93.
    2002 Stratos 20XL w/ 1998 Mercury 225 EFI

  9. #8
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    you'll be fine on 89.

  10. #9
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    Champions are recommended, but I run NGK Iridium's. Some seem to be able to run them and others can't. They sure resist fouling if you have to idle very much.
    "We, the unwilling, led by the unknowing, are doing the impossible for the ungrateful. We have done so much, for so long, with so little, we are now qualified to do anything with nothing."

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