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  1. #1
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    Mar 2016
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    2001 225 optimax engine misfire?

    2001 225 optimax
    SN# 0T333683

    Hi, yesterday when I took the boat out in morning I had a very distinct engine misfire, at least I think. When I left the no wake area then accelerated for hole shot there were two very distinct boom, boom or bang, bang sounds, as the rpm increased while the bow raised up. I would say it happened less than or up to 4000 rpm(which is about when the bow usually starts to drop but it didn't get there). I immediately cut the throttle to idle. the engine seemed normal. No miss or hesitation. I then accelerated again with a normal hole shot maybe 3-4 seconds for bow drop. Everything seemed fine, I then took engine on a long lake run up to max rpm of 5610 on smartcraft gauge. Boat was running at its normal max speed for the set up.

    I launched alone, so once i started the engine I always let it idle to warm up at the dock while I go and park the truck. Its then a 1/8 to 1/4 mile idle through the no wake zone before accelerating. I didn't actually look at the temp to verify engine temp, but it had been idling for maybe up to 10 minutes. Water temp yesterday was 82 and air temp was around 75 to 80 at around 7:30 am. Engine always started and ran normal the rest of the morning. only other thing is my cranking battery may be getting weak, as two times my bow graph shut off while i cranked engine. would low voltage cause a misfire even though it cranked and started fine?

    I've owned this boat for last 3 years and have never experienced any thing like this before. The engine has 241 hrs, had 185 when I got it in 2017. The boat hadn't been used in last 3 weeks. I did not put new gas in yesterday, but always use the mercury 1 and 2 additive when i add gas as well as marine stabil in case it sits for a long while. I replaced the water separator filter earlier this summer. Any ideas of this issue? bad gas? plugs?(I replaced them and wires after I bought the boat, 56 hours max on them), or just an isolated incident? I wont be able to run the boat till mid next week to see if anything returns. I hope I left enough info.
    Thanks in advance for any input
    2001 ChampioN 206
    Mercury Opti 225

  2. Member lpugh's Avatar
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    May 2009
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    Sacramento Ca
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    5,164
    #2
    Submerged log
    Lower unit problem, drain and inspect lube condition
    Thank You Leon Pugh

  3. Member
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    Mar 2016
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    #3
    Hmm, interesting, I would not have thought of the lower unit. Easy enough to change the gear lube.
    2001 ChampioN 206
    Mercury Opti 225

  4. Member
    Join Date
    May 2011
    Location
    Spangle, WA
    Posts
    6,180
    #4
    There's a recommended maintenance schedule in the FAQ you may find helpful also.
    _______

    Phil
    '09 Hewescraft ProV
    '09 150 Optimax


  5. Member
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    Mar 2016
    Location
    NRH, TX
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    61
    #5
    Thanks for reply's. Update: I drained and refilled lower unit gearlube, no water or metal shavings in oil. Looked normal. Removed prop, cleaned, and inspected. Nothing unusual with prop and shaft, no damage found, so lubed and torqued. Went and ran boat for 3 hours, it never missed a beat, ran great. So I must have hit a submerged log or something.
    2001 ChampioN 206
    Mercury Opti 225

  6. Member lpugh's Avatar
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    May 2009
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    Sacramento Ca
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    5,164
    #6
    Might be a good idea to check all engine mounting fastners just to be sure nothing is shifting
    Thank You Leon Pugh

  7. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    Apr 2008
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    Greenville, SC (US)
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    94,945
    #7
    And if for nothing other than a confirmation of condition (and a benchmark), it might be wise to perform a compression test.

    Reed inspection would also be wise.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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