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mercruiser ignition problems

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  • mercruiser ignition problems

    ok guys heres what i have its a 1986 mercruiser 140, with points ignition, i have a problem with keeping it running. it will stall out on me after a few minutes on the muffs at idle, @650 rpm., i did a complete tune up to see if that would help and its still dying out on me..if i take a wire from the +12 side of the battery to the + side of the coil it will run great, whats the best way to isolate whats wrong? i disconnected my temp wire as not to burn out the points with batt voltage. i also have a mercruiser resister kit installed in the harness going to the coil.


  • #2
    Re: mercruiser ignition problems

    Disconnect your boats fuel system at the engine fuel pump and hook up an outboard tank and see what it does.You could have problems with the fuel pickup, the antisiphon valve, hoses sucking air instead of fuel due to bad hoses or wrong clamps, plugged fuel tank vents or low spots in vent hose.
    Don S.

    sigpic

    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.

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    • #3
      Re: mercruiser ignition problems

      don, i cleaned the antisiphon valve, replced all fuel filters, installed a new factory mercarb, getting great fuel pressure, why is it if i hook up 12 volts to the plus side of the coil it runs better

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      • #4
        Re: mercruiser ignition problems

        You also did a tuneup. After you changed the points, did you set the dwell, and then reset the timing and adjust the carb?
        Don S.

        sigpic

        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.

        Comment



        • #5
          Re: mercruiser ignition problems

          don yes i did,

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          • #6
            Re: mercruiser ignition problems

            What is the voltage between the positive side of the coil and the block when it starts acting up?

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            • #7
              Re: mercruiser ignition problems

              You have made no mention of the coil. Did you change it. The coil is mounted close to the block and gets pretty hot after a few minutes. An intermitten coil will give you some similiar symptoms. If it is an 86 model coil it is due for a change. often mistaken for carb problems.Uncle Dave

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              • #8
                Re: mercruiser ignition problems

                i'll check in the morning and post

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                • #9
                  Re: mercruiser ignition problems

                  coil has not been changed to my knowledge

                  Comment



                  • #10
                    Re: mercruiser ignition problems

                    You also need to check the resistance from the 'ON' side of the key switch to the coil "+". It sounds like you have a resistive wire going faulty. Does the engine slowly die out, or is running great then just die, like the key has been turned off?You say you have a restistive wire kit installed. Is this in series (in line) with the original or does it replace the original?Chris............
                    The world takes on a whole new perspective when viewed from 100' below...



                    1972 Bertram 'Bahia Mar' 20
                    2006 Mercruiser 4.3MPI (0W617679) w/Alpha 1 Gen II (0W829301)
                    **
                    Please don't send service questions in private messages. That's what the forum is for. Messages of thanks, always accepted.
                    **
                    Member of the month - April 2013. http://www.iboats.com/blog/achris-member-of-the-month/

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                    • #11
                      Re: mercruiser ignition problems

                      Chris,it dies a slow, reistor replaces the original

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                      • #12
                        Re: mercruiser ignition problems

                        thanks guys it was a bad coil, replaced it today it runs great now

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