Learn me some 'lectrics: not starting.

Discussion in 'Dakar champion (950/990)' started by tomdubz, Nov 23, 2019.

  1. tomdubz

    tomdubz getting there Supporter

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    '09 990

    Bike power died while riding. Was able to restart and limp to a parking lot. At home, it started and ran for about 5 seconds. Now nothing. Behaving like dead battery.

    Tried two different batteries. Both fully charged between 12.7-13 V. When ignition engages, voltage drops to 6-8. Makes that weak start, not gonna turn over noise.



    Disconnected, the batteries are back to fully charged. Does that mean they're fine? If so, what else could cause this?

    Cables and connectors are mostly fine. Some 80k mile rubbing on housings but nothing really exposed.

    Maybe this is why my abs hasn't been working.
    IMG_20191123_161041.jpg
    Or maybe this.
    IMG_20191123_161147.jpg

    No blown fuses. Grounds connected.

    Not losing current. 0.6-0.7 mA so not the regulator.

    Generator coils resistance at 0 ohms so no stator problems?

    What's next? All that starter relay stuff? I'm scared someoneholdmyhand.
    #1
  2. soupbone

    soupbone Been here awhile Supporter

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    Bad battery. Voltages should be above 12 when she cranks. Low voltages make weird things happen to these bikes.
    #2
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  3. tomdubz

    tomdubz getting there Supporter

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    But, but, I hope it's that simple. Even though they read high before and after the ignition attempts? There's nothing else that could cause a drop from normal to 6-8V when starting?
    #3
  4. DirtyADV

    DirtyADV Long timer

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    Would also say battery is the most likely cause.

    If you want to confirm battery, try jumper cables and see if it fires then, if so for sure battery is toast.

    /Johan
    #4
  5. emmodg

    emmodg Been here awhile

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    The little ecu's on most "newer" (FI) bikes require "factory correct" voltage, and they require this at the same time your starter and pump and lights are "asking" for their respective battery voltage. Little motorcycle batteries are taxed quite a bit and now couple that with dirty connections and sometimes weeks (or months) sitting in a shed with no charge and you've got a problem like yours. You need a battery with over 13volts to crank the old girl over.
    #5
  6. Zuber

    Zuber Zoob Supporter

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    Yup, sounds like battery. These AGM batteries fail in a weird way. They will charge up in a minute and look like they have full voltage (13.2v). But, if you apply any kind of load, the voltage drops way down.
    After you get it started, check the charging voltage for a bad Reg/Rec. Running a weak battery will stress this weak thing. Should not go over 14.2-14.5v at 4000 rpm. Should also charge 13.8 or more at idle.
    #6
  7. tomdubz

    tomdubz getting there Supporter

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    Jump starting didn't do the trick. So, maybe not the battery. When hooked up to a running car, voltage across the poles at bike battery went from 14.5ish down to 12.5ish. Should be enough for a start but still just doing what it was doing in my video above. Not even turning over.

    Fwiw, I ride 2 or 3 times a week. 1 battery is 6 months old and the other is brand new.

    What else could it be?
    #7
  8. Zuber

    Zuber Zoob Supporter

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    With good battery, you must have a big voltage drop somewhere. Do the big cables get hot? Esp. check the starter relay connections, it's down in the dirt and is a known problem.

    Easy way to check cables and connections - connect a voltmeter across a long run, like from the battery + to the terminal on the starter relay. When you hit the starter, there should be next to no difference in voltage between these two points. Any voltage you see here will be subtracted from what the ECU/Starter sees. Check across the starter relay. Check the battery ground terminal to engine block.
    #8
  9. tomdubz

    tomdubz getting there Supporter

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    I didn't feel cables getting hot but I'm only hooking things up for a minute or two. Starter relay gets cleaned 2 or 3 times a year and I'm not feeling any heat there. It is clicking like it should.

    I think I know what you mean with the tests:

    - cold unhooked battery 13.5V
    - hooked up 13.4V
    - across starter relay 13.5
    - long run - negative batt terminal to starter relay 13.5
    - positive battery terminal to engine block ground, up next to starter 13.5
    - negative batt terminal to positive feed at the starter 0 (is this b/c it goes to a relay first?)

    - with key turned on across the poles, across starter relay, and long run were all 12.5ish - negative batt terminal to positive feed at the starter was 0.8V (normal?)

    -with ignition engaging everything was dropping like it shouldn't. Neg batt terminal to hot starter feed was most erratic, going from 0.8 to negative numbers to 5ish. Is that where my problem is somehow? don't see any breaks in that cable.

    Here's a shitty video that highlights my confusion:
    #9
  10. Zuber

    Zuber Zoob Supporter

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    The last two tests are what I was talking about. Getting 0.8v along the negative cable is bad, but that could have been from the jumper cables.

    Jumper cables can't carry enough current to work, get rid of them for this test and repeat.
    Negative battery POST to starter case. Hit the starter. Should have only 0.1v or less for all tests.
    Repeat for Positive battery POST to the hot post on the starter. Hit the starter. Less than 0.1v.
    If you get a bigger number, split the difference. Try to pinpoint the exact point of voltage loss.

    My rule: "If it acts really wacky, clean all the grounds"
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  11. charlie264

    charlie264 Long timer

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    First, you need good connections, crock clips wont cut it. Is the battery good? If when cranking if it drops below 10- 10.5V is has low cranking amps. Most common for the symptoms you are having is a poor ground/earth connection. Clean and re-torque. There are two lives to the starter motor relay, one is an exciter which has no voltage until you hit the starter button. The other is a constant live.

    Also the cables with the green rot, they need replacing.
    #11
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  12. tomdubz

    tomdubz getting there Supporter

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    Whelp. This is going to have to be continued. In an effort to feel like I accomplished something I went and removed my front oil line (from the top of the tank down to the other side of the motor) because it was corroded on the bottom. Also, there was so much gunked up oil in that narrow channel where it lives with the wires heading to the starter that I couldn't clean and inspect and I wondered if it was leaking from the hose to pipe junction. I had to cut the line to get it out and now I'm having an issue getting a new one back in there. Funny thing is the line itself looks like it wasn't compromised and all that gunked up oil was likely from that one time I lost count of how many quarts I refilled. Looks like I'm going to have to take the front motor mounts off in order to have the space.

    Anyone else have experience with a better idea?

    Knowing me, my cheap amazon batteries probably aren't good and the jumping them from a car test failed due to my chain of jumper cables. Yes, I'm an idiot. Thank you all for the patience and advice. I'll be back to fucking things up as regularly scheduled next weekend.
    #12
  13. Dusty

    Dusty Long timer

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    About 5 months back while doing a valve check and radiator cleaning i noticed that the end of the hose that goes into the oil tank was cracking and getting brittle so i had another line of a newer motor so i swapped that line out, it was a bit tricky with all that i had off already.

    I did remove the engine support, i was able to clean up the wiring routing also. I would take a good look at that hose now that you're into it. When replacing the hose make sure to get the height and angle set right before clamping it down, it slides down the metal line quite a bit.

    [​IMG]
    #13
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  14. Problem0

    Problem0 Adventurer

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    Clean the terminals at the starter motor and refasten them. You probably have a high resistance between the earth terminal there and the battery. This looks like a battery fault because the battery voltage seems to drop, but it isn't, it's dropping the voltage over the resistance at the terminal.
    #14
  15. Zuber

    Zuber Zoob Supporter

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    It could be a common problem that is showing in a weird way. The wires going to the ignition switch will break from flexing.
    #15
  16. tomdubz

    tomdubz getting there Supporter

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    This worked. Never did really pinpoint, but likely where the battery grounds into the starter as I had a hard time getting a reading there. Took them all apart, doused the areas in electronic cleaner, got jiggy with my wife's toothbrush, and fine sandpaper for the terminals themselves.

    After dealing with the rat fuck that is the front oil line, rebuilding the battery box, and hooking it all back together, it fired right up.

    Fwiw, I was able to replace the oil line by only removing the right side engine support and the front header (bolt was put in the wrong side per the fiche, so header was in the way). If this prevents someone from freaking out about that...

    IMG_20191128_155517.jpg

    Now, all I need to do is find that little rubber doohicky that mounts the abs fuses. Good times. Maybe I'll ask for a lift for my 40th bday.

    I'm thankful for all you FFs that held my hand.
    #16