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Optimax question for the Merc gurus...

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  • Optimax question for the Merc gurus...

    I have a 2008 Optimax 175 that I suspect a ECM (computer) problem.

    The question:

    Will an ECM from a 2008 Optimax PRO XS 175 work on a non-PRO engine to do testing to confirm if a defective ECM is the issue?
    1992 211 w/175 OptiMax
    Glen Campbell, Pa.

  • #2
    Call SIA in Illinois

    They rebuild and support the computers and always answer questions like this

    P.O. Box 392

    730 North Minnie St.

    Tilden, IL 62292

    Phone: (800) 737-0915

    Phone: (618) 587-3308


    • #3
      Called SIA...

      No luck - they don't do outboard computers...
      1992 211 w/175 OptiMax
      Glen Campbell, Pa.


      • #4
        Why do you think it's a ECM issue? Did you have a few coils go south?


        • #5
          This one has me stumped...

          Idles really rough, throttles up but still rough.

          Stalls at idle, but will restart right away.

          Had fuel injectors and air injectors cleaned and serviced.

          Cleaned fuel rails & lines, cleaned pumps.

          Replaced filters, running from spare tank with fresh non-eth fuel.

          Installed know good ignition coils from running Opti 175.

          Cleaned fuel and air pressure regulators, installed new tracker valve.

          Done full print out with Diacom software, nothing looks out of place on the readings.

          110 to 115 compression on all 6 cylinders.

          Air pressure on rail is 80 PSI.

          Fuel pressure on rail is running 90 to 92 PSI.

          Did the "drop test" with the Diacom software, each cylinder exhibits an RPM drop when individual cylinders are shut down.

          Any ideas????
          1992 211 w/175 OptiMax
          Glen Campbell, Pa.


          • #6
            Have you asked around on the bass barn? They have some good guys over there. Helped me with mine. Had a coil that would over heat after 15-20 min.


            • #7
              TPS, MAP sensor and crank position sensor are key input sensors as well for idle.


              • #8
                I believe those engines still have a mechanical lift pump to supply fuel to the high pressure system....Those mechanical pumps (if it has one) can fail and dump fuel into the crankcase...Had it happen on 3 mercs now....

                just a thought...

                [br]1994 Mako 215 Dual console Optimax 225[br]1978 Mako 19 with 90hp johnson[br]1996 Mako 22[br]1982 Mako 171 Angler 135 Black Max Mercury[br]1987 21b 225 Yamaha[br]1974 23 inboard Gusto gone.[br]1979m21 225johnson \"blue dolphin\" bought off this board and restored [br]with everyone\'s help!!Gone but not Forgotten....[br]1979 20 Mako 115 Suzuki gone[br]1977 19 Mako 115 Johnson gone[br]1976 23 Mako twin 140 Johnsons gone[br]1983 224 with closed transom and bracket[br]And 162 SOB (some other boats)[br]Venice Florida, Traverse city Mi.


                • #9
                  Any update? The suggestions listed seem like the right areas to look at.
                  Boca Raton, FL[br]Current: 2002 253[br]Former: 1995 19[br]Former: 1979 19b


                  • #10
                    No update, vacation and work has kept me away from it for a while.

                    It does have the manual pump on the side of the block along with a low pressure pump mounted on a bracket on the side of the high pressure pump.

                    Very odd configuration in my mind...
                    1992 211 w/175 OptiMax
                    Glen Campbell, Pa.


                    • #11
                      Finally an update with good news...

                      After changing the lift pump without any improvement, decided to swap the ECU from another engine.

                      Hit the key and it fired right up and idled smooth as day one when she was new!

                      Kicked it up to higher revs (2000ish) and made the transition without any hesitation or vibration.

                      My trust in Mercury outboards may have actually been restored!
                      1992 211 w/175 OptiMax
                      Glen Campbell, Pa.