Electrical leak

Discussion in 'Parallel Universe' started by barbarian, Sep 12, 2013.

  1. barbarian

    barbarian Barbarian

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    Hi everybody,

    This is my first post on your forum which I check regularly as there's tons on useful informations and contributors. So thank you everybody for keeping the flow running.

    I have just replaced my F800GS engine by another one as I destroyed the other one (piston smashed among other damages following a spark plug failure). It was a lot of work and I now feel very frustrated because of an electrical leakage which prevents the starter motor to have enough power.

    This is how I tested : unplug the negative - of the battery and use a voltmeter between the negative and the frame. I identified the followings connectors that generate a leakage tension :
    • Starter motor = 12V
    • Oil pressure switch = 12V
    • Oxygen sensor = 9,5V

    When we pulled down the engine, we forgot a few connectors which were then under tension (no break) but hey now I think it's an evidence, I screw up.

    Well, would you have any ideas as I'm more or less stuck right now. It looks like I may have to identify the dodgy cable(s). Any input is much appreciated.

    Cheers
    #1
  2. Full Power

    Full Power Long timer

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    You misunderstand the voltmeter indication.
    What the voltmeter is telling you is that your BATTERY voltage is 12, and is in need of a full charge.
    CHARGE the battery, it should rest around 12.8 volts, which should start your F8.
    #2
  3. barbarian

    barbarian Barbarian

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    Well it's actually indicating 12.8 indeed. But by no means I should have tension on the frame.
    #3
  4. Full Power

    Full Power Long timer

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    I doubt you have "tension" on your motorcycle frame.
    Connect your 12.8 volt battery, wait a few days, and then check the resting battery voltage.
    If it is still up at 12.75 or better, you can stop chasing ghosts.
    #4
  5. ebrabaek

    ebrabaek Long timer

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    I want to make sure I understand exactly what you are saying. Are you trying to check the discharge rate with the battery connected...??? ( leakage) to see if there is a drain on the battery after all is turned of....???? If that is the case you then need to disconnect the neg. cable from the battery, as you did, but the volt meter should be in amp. mode, and one probe should be on the frame, and the other one on the neg. bat. terminal. After 30 seconds and the bmsk. shuts down, and disconnects the cigarette plug, you should see under 5 milli amps, ( 0.005 amps). If you see any more, something is draining your battery, and you need to try to trace it. If this is NOT what you are trying to do, then forget about the above suggestions, and please explain further.
    #5
  6. barbarian

    barbarian Barbarian

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    Thanks for your help, so let me try to explain further what I'm trying to accomplish (I'm french and although I used to live in the UK, excuse my english please) :

    When trying to start the engine, the starter motor seems to run but seems weak (I dismantled it and all seems fine and up and running), I haven't checked it with a direct connection though. But I can hear it rotating when hitting the starter button, it does not seem to engage the engine though.

    Suprised about this, we thought we'll check the battery voltage, it was fine, then we checked for electrical leakage, the operating mode is to leave the battery + connected, then check the - on the frame (- disconnected and a multimeter in between).

    We should always have 0 then ! Which is always the case, apart when I connect one or all of the following elements :
    • Starter motor
    • Oil pressure switch
    • Oxygen sensor

    Hope this is a little clearer.

    Maybe I plugged the starter motor the other way around, would it be rotating then ?

    Cheers
    #6
  7. Warin

    Warin Retired

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    Your multimeter has at least 3 functions

    1) voltmeter - to measure potential difference (units volts)

    2) current meter - to measure the flow of current (units Ampres or amps for short)

    3) resistance meter (or ohm meter) to measure resistance (units ohms)

    --------------------
    To measure the drain/discharge of your battery you need to measure the current flow .. so you need to select the current meter function of your multimeter AND usually change the connection of the leads - volts and ohms are on one terminal - and current is usually on another terminal - with yet another terminal being common for all functions.

    While 0 amps is ideal .. you'll probably have some leakage ... less than 0.01 amps (or 10 milli amps) is more realistic. THIS IS WITH THE BIKE TURNED OFF!

    =========================
    If the battery is freshly charged and not long on the bike then any discharge should not have had time to have too much effect on the battery. So with a freshly charged battery you should be able to start the bike. If not then you have a different problem.

    =====================
    The starter motor will only have ONE large terminal .. the other connection side of the starter motor is the chassis of the motor. You cannot get that wrong. You could connect the small terminal of the solenoid incorrectly .. there should be a size difference between the two .. the large one goes to the battery. The smaller one goes off to a relay or handle bar button depending on the bikes wiring. Some starter motors have the solenoid bolts up to them - all one physical part.
    #7
  8. ebrabaek

    ebrabaek Long timer

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    Ok.... got it.
    Warin explained it very well above. Use the negative side of the battery, and measure between the battery, and frame. You had it correct, except , you need to be in AMP mode on your multimeter..... NOT VOLT. Try it again, and post your results. It is known that there are/can be issues with the stock charging system, and to make sure yours is good. The following thread is a write up I did on the diagnosis on the charging system. Read it, and go through all the measurements, and post the results. With that in hand, we shall have a look of what you have going on.

    http://advrider.com/forums/showthread.php?t=809879
    #8
  9. barbarian

    barbarian Barbarian

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    Hi there,

    I thought I'd check the starter motor and it was all fine. Finally I got to start the bike reverting the way the starter motor was plugged, I put the red cable on the frame (which does not make sense to me) and the black one on the starter.

    The bike starts ! BUT, of course there is a but, very soon after (like 1,5s) I can hear a spark outside. There's a short circuit somewhere.

    How can I dectect where it comes from ? I'm definitely a novice in terms of electricity and eager to learn.

    Thanks guys for the support.
    #9
  10. ebrabaek

    ebrabaek Long timer

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    Keep repeating, until you locate it...... LOL... sorry, could not resist. If it is big enough to make a bang you can see it... Start looking. Sorry, but this is something out of the ordinary. Start following wires until you find something burned.
    #10
  11. barbarian

    barbarian Barbarian

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    Well I'd rather find a better way. Restoring my F800GS is costing me a hell of a lot of cash, I can't afford to ruin the ECU.
    #11
  12. Pangit

    Pangit Been here awhile

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    Keep going and it will cost you even more. Save money, take it to a professional.
    #12
  13. barbarian

    barbarian Barbarian

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    If I have no more clues and things to try safely, this is what I'm going to do, it's a shame at that step of the restore, but hey when you don't have the tools (and software) there's not much you can do.

    Things would have been much easier with a good old fashioned fused harness.
    #13
  14. barbarian

    barbarian Barbarian

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    Hi all,

    Beeing stubborn but methodical pays off. The short circuit came from the temperature sensor. The new engine is up and running, and all is well.

    Thanks for the constructive inputs.

    I'm happy and so is my resurected F800GS :rayof
    #14
  15. ebrabaek

    ebrabaek Long timer

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    Awesome.....:clap
    #15
  16. Loutre

    Loutre Cosmopolitan Adv

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    cela fait plaisir à entendre! félicitation!:clap

    (nice to hear!)
    #16
  17. barbarian

    barbarian Barbarian

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    Oui, il s'en est passé du chemin entre la dépose du moteur et mon cul sur la selle! 6 soirées bien remplies.

    Thanks for the support. Safe rides to everybody.
    #17