Can anybody explain Mercury outboard issue

Discussion in 'Outboards' started by slneatboat, Sep 6, 2015.

  1. slneatboat
    Joined: Nov 2003
    Posts: 29
    Likes: 1, Points: 3, Legacy Rep: 20
    Location: Norfolk,England

    slneatboat Junior Member

    I hope there is a simple explanation as I am no mechanic,
    1997 Mercury 50hp 4 stroke
    Has been running fine but started it yesterday and it ran really rough and lumpy like it was only on 3 cylinders, turned it on and off a couple of times went down river for 10 minutes to see if it would clear to no avail .Went to start it again after about an hour and everything was dead so figured the battery was flat.
    Went to it today and it started straight away and is running fine the only thing is I put a meter on the battery and it read that it was over charging and 16.50 amps, so changed the battery and it is no longer over charging and 13.50 amps. went out for a 2 hour cruise no troubles.
    Could it have been the battery making the engine run rough ?
    Thanks
    Steven
     
  2. gonzo
    Joined: Aug 2002
    Posts: 13,609
    Likes: 382, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    I assume you meant 16.50 volts and 13.50 volts. If so, that would cause a problem. Either too low or too high a voltage is bad.
     
  3. slneatboat
    Joined: Nov 2003
    Posts: 29
    Likes: 1, Points: 3, Legacy Rep: 20
    Location: Norfolk,England

    slneatboat Junior Member

    Yes I did mean volts, I tested the battery when the engine was running. Just wondered if the battery was duff and the engine was trying to charge it to much would that have made it run lumpy.
    Steve
     
  4. slneatboat
    Joined: Nov 2003
    Posts: 29
    Likes: 1, Points: 3, Legacy Rep: 20
    Location: Norfolk,England

    slneatboat Junior Member

    Back to square one, went out couple days ago for about an hour and I noticed that the trim on the outboard had altered , the rocker switch is on the throttle control and I must have leant on it and altered it a little, anyway went to alter it back and nothing happened it was still running at this time. I thought I would switch off and try it still nothing, went to start again turned the key completely dead. Fortunately was in a mooring area and not in the middle of nowhere. Left the boat there and let a boat yard tow it in next day but they haven't looked at it yet but say I perhaps put on another duff battery but I am not convinced.
    Any thoughts ?
     

  5. slneatboat
    Joined: Nov 2003
    Posts: 29
    Likes: 1, Points: 3, Legacy Rep: 20
    Location: Norfolk,England

    slneatboat Junior Member

    Just to update boat yard says a fuse had blown, the battery is no good and it needs a new rectifier. Can only think it was overcharging and blowing the battery.
     
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