Electrical problems in a 50 hp Mercury?

Discussion in 'Bubba's Outboards' started by Catgirl, Mar 15, 2007.

  1. Catgirl

    Catgirl New Member

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    13,546
    Hey Willard and Bob,
    I was just reading all your posts in this forum and wanted to say thanks on behalf of the many people you have assisted. It's appreciated :smile2:!
    Now on to my question :lol:.

    The motor: 1990 50 hp Mercury outboard - it's on a 20 foot pontoon boat; need to know HOW to specifically test the starter to find out if it's gettin' enough voltage and amperage to turn it (in order to make sure the key switch is not bad). When you turn the key, something clicks in the motor, but the starter doesn't spin at all. Have access to just about every electrical tester there is.....

    Thanks in advance for your help fellas :cool2:.
     
  2. Mr.T

    Mr.T Active Member

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    2,554
    State:
    MO
    A Clymer or SELOC service manual for your make and model of motor will contain a complete procedure for troubleshooting the electrical system. If you're going to work on your own motor, you *really* need a manual - it's around $25 or so, maybe less, from any marine parts dealer or various sources online. I prefer Clymer brand personally but either should be suitable.

    Bob and/or Bubba may be able to explain the procedure here, but it'd be a lot faster and easier to use the manual - plus there are pictures in the manual that are worth, well, about a thousand words each.
     

  3. Catgirl

    Catgirl New Member

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    13,546
    Hey Marty.....yes, we've looked a few places in the area for a manual and still may be able to find one. However, the boat is needed on SATURDAY, and I don't think I have time to order one online if we can proceed under the motor guru's direction here :smile2:. Don't worry, I probably won't even get to touch anything. After the week I've had, I'm liable to fry myself :lol:!
     
  4. jim

    jim New Member

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    2,579
    State:
    Jacksonville NC
    Are we assuming the battery is fully charged?It might show 12 volts but not have enough amps to roll that Merc over.What little I know, if you hear the click the solenoid is good and you should be able to see if the arm on the starter engages or attempts to,the flywheel.It might be stuck in the engaged position and if so a gentle tap can cause it to retract.Who is turning the key?I can't imagine that Mercury not starting for the Queen of Carolina!!!!:big_smile: :lol: :eek:oooh: :wink:
     
  5. Catgirl

    Catgirl New Member

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    13,546
    Hmmm......hadn't thought of that Jim, and it HASN'T been ME turning the key :wink:!
     
  6. Bubbakat

    Bubbakat New Member

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    4,532
    State:
    McMinnvill
    This is what the book says to do. Me I have a shorter way but hard to put into words.

    Fist let it be known never use an auto solenoid for marine use.

    This test must be preformed with the solenoid off the engine
    Connect one test lead of an ohm-meter to each one of the solenoids big terminals.
    Connect the positive lead from a fully charged battery to the small terminal on the solenoid marked S

    Take your ground lead from the battery and touch the other small terminal marked I and if a loud click is heard and the ohm-meter shows continuity them most likely the solenoid is in working order.
    If you hear a loud click and the ohm-meter doesn't show continuity then it needs to be replaced with a marine type solenoid.

    If you are having trouble identifying the two small solenoid post the turn the solenoid upside down with the flat part sticking up and the post on the left will be the I post that is the one the wire from the key switch goes to.

    The s terminal is on the right and goes to the safety switch or ground.

    Before I did all this I would clean every connection from the battery to motor and solenoid. I don't mean with a rag I am talking a file or wire brush in a drill
    Hope this helps and make sure the battery is fully charged and pay close attention to the cable ends because they can go bad over the winter while sitting that is why I recommend removing the battery in the winter.
     
  7. psychomekanik

    psychomekanik New Member

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    2,534
    State:
    Illinois
    I have a quick test for ya'. we do it all the time to diagnose starters in cars. hold the key in the crank position, and GENTLY tap the starter with a hammer a couple times. if it turns over, you most likely have an open winding in the armature, or poor brush contact. i know it sounds crude. but it's an old proven shortcut. you might look into having it rewound. and, a lot of the times it will last you for some time before it stops on the dead spot again to give you more trouble.
     
  8. ncfowler

    ncfowler Well-Known Member

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    2,648
    State:
    NC
    Name:
    Jeff
    ok i just got to ask a dumb queston, is the motor out of gear? most motors have a saftey so it will not start up in gear, also check your battery connections for oxidation and all the connectons are tight.
     
  9. Bubbakat

    Bubbakat New Member

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    4,532
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    Good question but if it was out of gear then no clicking or anything would be heard because the safty switch would kill all fire going to the solenoid.
     
  10. Bobpaul

    Bobpaul New Member

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    3,039
    State:
    Supply NC
    You can jump the solenoid from the large stud on the battery side to the small stud with the yellow/red tracer wire.

    If the battery is fully charged and connections are clean and tight, the solenoid will engage and the starter should turn. You don't have to have the key in the on position for this, in fact you shouldn't have the key on.

    If the solenoid engages and nothing else happens, it's probably the starter.

    If everything is trying to work and the engine still won't turn over, it could be engine trouble.
     
  11. glenmorebuckman

    glenmorebuckman New Member

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    153
    State:
    Caneyville, Ken
    Bubbakat, I hate to show my ignorance here, but everyone will find out sooner or later:embarassed: My Mercury 35 h.p. has a solenoid on the starter that appears to be almost like the solenoid on a Ford engine. I do know the Merc solenoid has an extra post for a ground wire. My question is {please forgive me} why couldn't this be used on an outboard?
     
  12. Bubbakat

    Bubbakat New Member

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    4,532
    State:
    McMinnvill


    The marine solenoid is grounded thru the mounting bracket and the auto solenoid is grounded thru the s post that goes back to the switch. The theory is that it could cause a spark and that could prove to be hazardous considering every thing is grounded back to the battery and back to the motor. There is no metal frame to ground to like and auto.
     
  13. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill


    Thanks Bob that is the way I would do it here at home but I just couldn't put the right words to it.:tounge_out: