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  1. #1
    Member
    Join Date
    May 2013
    Location
    Houston Tx
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    4

    Intermittent High RPM at idle, with Interrmitent loss of Rpm undrway

    2013 200 PRO XS 247HRS
    Serial# 2B018914

    Wanted to get the collective experts thoughts. I've had this issue for a couple of months now. Motor has intermittent issue of dropping RPMS suddenly when underway for maybe 1/4 of a second..then running fine. She also has a intermittent issue where after coming off plane and going to neutral she high idles. I can re-engage the throttle and it runs correctly then back to neutral she high idles again. If I turn it off, then turn it back on it idles as it should and runs fine. I've taken it to my veteran (25yr+) certified mercury mechanic 2x. He did a sea trial and got her to cutout for less than a second once and then could never get it to repeat the issue over next hour. He ran resistance/pin out tests on all coils, ran air and fuel injector pop tests and they were consistent, Ran ohms check on all spark plug wires, ran spark test and all within spec. Checked Schrader valves and air fuel pressures were normal and good. I've done some searching on here and it sounds like the likely culprit is the TPS/TPI or a diaphram. She runs like a top other than that. No alarms on my Mercmonitor, or really off numbers on the gauge. That being said I'm not yet totally savvy on all the nunances of this motor as my last motor was a carburated yamaha. Just wanted to get yalls take before I just start throwing parts at it. My mechanics advice is run it till it does it constantly/consistently so he can diagnose it. Which I do understand his position...he put a easy 8hrs in chasing this with no joy and didn't charge me almost anything as he couldn't pin down the issue. From reading and researching it sounded like the above TPS/TPI was highly likely and something I could do myself whereas changing the diaphram is a bit harder diy. As always thanks for your time and tight lines!!
    Last edited by parafirediesel; 07-31-2021 at 04:37 PM.

  2. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    Apr 2008
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    #2
    I'd be looking at the TPS as a highly-probable culprit. May not necessarily have faults- but a voltage sweep test (or recording of the engine while it is doing this) may lend DATA to indicate the sensor is providing erratic readings.


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  3. Member
    Join Date
    May 2013
    Location
    Houston Tx
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    4
    #3
    Thanks Don!