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  1. #1

    Default Converting EFI to Carb 4.3 Mercruiser

    What would be involved and necessary to convert an EFI TBI setup to Carb? This is a 2000 Model year engine. The new ECM conversion kit is just too costly to purchase. Considering converting to Carb to avoid the 3500.00 expense.

  2. #2
    Vice Admiral Tail_Gunner's Avatar
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    Default Re: Converting EFI to Carb 4.3 Mercruiser

    Quote Originally Posted by get-r-done View Post
    What would be involved and necessary to convert an EFI TBI setup to Carb? This is a 2000 Model year engine. The new ECM conversion kit is just too costly to purchase. Considering converting to Carb to avoid the 3500.00 expense.
    What is the problem with the old system?? There a little eaiser to repair than you might think.
    Stickly a opinion your milage may vary.

    Speed is how fast you hit the wall
    Torque is how far you move the wall"

  3. #3
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: Converting EFI to Carb 4.3 Mercruiser

    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.

  4. #4
    Vice Admiral Tail_Gunner's Avatar
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    Default Re: Converting EFI to Carb 4.3 Mercruiser

    Ive been there..It seems to me your dropping a efi motor into a boat that is not wired for it..duh.. so take off the intake ..pull off all the wiring and get that pigtail i posted in the other thread opps and probably a new elect fuel pump

    Your going to have to rewire the motor there are no patchwork..work arounds..Its seems like a big job but its not as long as either you or mech has a full understanding of the wiring and what he needs to do.

    1. new fuel pump your 4.3 does not have provisons for a mech pump
    http://www.ecrater.com/product.php?pid=4057198

    2. There's the plug it should plug right into your old boat
    http://www.cpperformance.com/detail.aspx?ID=838

    3. One good person who knows wiring its not that tough if you know where your going
    Stickly a opinion your milage may vary.

    Speed is how fast you hit the wall
    Torque is how far you move the wall"

  5. #5

    Default Re: Converting EFI to Carb 4.3 Mercruiser

    What is the problem with the old system?? There a little eaiser to repair than you might think.
    The problem is that there is an option set for "load anticipation mode" According to the mechanic he believes this is leaving the engine at base time mode all the time. He is claiming that at any throttle position, the timing will not advance. It sounds to me that the signal is expecting a ground to work properly. If I am missing something from a previous post my apoligies, but I don't see anything from old wiring that would change this setting if it truly is the problem. Don by all means jump in there and and explain.

    Thanks

    MIE Inboards Only
    Load Anticipation Mode:
    The Load Anticipation mode is on MIE inboard and ski engines only. The function is used to help inboard engines during shifting. An electrical signal from the neutral safety switch (on the transmission) goes to the ECM on J2-20. This signal tells the ECM if the switch is closed or open. In neutral gear, the neutral safety switch is closed (signal grounded). When shifting into gear, the switch opens (signal open). When the transmission is shifted into gear, the open signal causes the ECM to add a calibrated amount of bypass air with the IAC. This is done to increase the load handling capability
    of the engine when going into gear on larger boats. When shifting back into neutral gear, the additional IAC bypass air is removed in an attempt to limit engine rpm flares. The amount of IAC air used is constantly monitored by the ECM. After the transmission is shifted, and the engine has stabilized, the ECM calculates an ‘error band’ from the Moving Desired RPM mode and adjusts the Load Anticipation mode IAC count accordingly. This allows the ECM to ‘learn’ the best IAC bypass air position to use for shifting each particular boat. NOTE: The Load Anticipation mode is on MIE 454/502 cid inboard engines also.

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