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Mercury 3.0 engine dropping RPM-gctid813920

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    Mercury 3.0 engine dropping RPM-gctid813920

    Engine was professionally winterized last fall and stabilizer added to fuel tank. First time out this year topped off the tank with Premium fuel (with 10% ethanol). Ran OK for several hours....burned off half a tank or so....noticed a bit of RPM drop occasionally every 15-30 seconds, but nothing really serious. Filled the tank with another 7 gal of Premium fuel last weekend. Boat ran fine for 10-15 min, then stopped (dropped into "Guardian Mode" I think) and two long beeps. Engine didn't stop. Put into idle and sat for a few further hiccups. Started again and within about 5 min did the same thing (dropped into Guardian Mode). It will limp along in idle with no further issues. Never stalls or stops running. As it gets warmer, it seems to happen more frequently. Very sudden stop, but with continued occasional RPM drop (not a lot, just 50-100 rpm) until WHAM, dead stop (engine still running). Has stalled once, but started right up again.

    Am thinking: 1) bad fuel or 2) the shop fogged the engine (it is fuel-injected) and thus messed up the sensors or 3) perhaps a oil pressure or temp sensor has gone bad. None of the engine readings are abnormal....all are in spec.

    Is it worth trying to drain out the fuel tank, refilling with ethanol-free fuel + ISO Heet, or do I bring it right back to the dealer (about 50 miles tow) since it is still under warrantee?
    Lake Memphremagog, Newport, VT
    2015 Bayliner 175 BR
    Mercruiser 135/3.0 MPI Alpha One

    Back to the dealer, YOU DO NOT WANT TO VOID YOUR WARRANTY !
    Be good, be happy, for tomorrow is promised to no man !

    1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

    '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

    Manalapan N.J


      No brainer in my hour drive is worth thousands...
      Lake Hartwell, GA
      2012 BR 185 - 3.0 TKS
      1999 Chaparral 233 Sunesta Ltd., 5.0 Volvo
      1987 SeaRay 300 - Twin 454’s
      1993 Yamaha Waverunner III VXR
      1993 Yamaha Waverunner III
      1995 Yamaha Waverunner III GP
      1995 Yamaha Waverunner III VXR PRO
      1996 SeaDoo GTX
      1999 SeaDoo GTX


        Catalyst, 2 O2 sensors on your exhaust system?

        Ran out of fuel in the past?

        Battery fully charged, in good shape?

        3.0 MPI,PCM09, complicated system.

        Possible cause...low battery voltage, low water pressure, over rev, low gear lube, low oil pressure, overheating...

        Yup, back to the dealer.
        Joon, Kathy, Jaden & Tristan
        Uniflite 42 AC, DD 671N
        93 3058 sold
        92 2855 (day boat)
        91 Fourwinns 205 (lake boat)
        Longbranch WA
        Life is Good


          Turned out to be a chafed wire shorting out intermittently -- fixed under warranty. Had the boat back out yesterday for a couple of hours running around at a variety of speeds and lots of turns and not a single hiccup. No hesitation and no stalling out issues remaining. Shop had it done in less than a week, but poor weather kept us off the water until now.
          Lake Memphremagog, Newport, VT
          2015 Bayliner 175 BR
          Mercruiser 135/3.0 MPI Alpha One