Anyone good with motorbike electrics?

Discussion in 'Cars, Bikes 'n AFVs' started by the_beer_man, Jun 19, 2011.

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  1. Specifically a 2001 CBR 939 blade?

    My fuel pump has stopped priming when I turn the key. Cutting a long story short it died after a days riding. Pulled over, switched the engine off using the kill switch, went to start and it wouldn't. If I run power directly to the pump it fires up.

    Do far I've tested:

    BAS- good
    Fuel cut off relay- good
    Ignition relay- good
    Kill switch- good
    HISS connection/different key- good
    Main earthing point and block- good
    All fuses- good
    Clutch switch- good
    Sidestand switch- good
    Fully charged battery- good

    I'm stumped. Saving at the moment to put it into a garage but just want to pick an outsiders brain. A point to note is that I have power going into the relay but no power coming out (problem with the ECM?).

    Cheers guys.

  2. You may get more luck with a blade specific forum as this may be a unique issue that is common to this model.


    If you have power into the relay and nothing coming out, why do you say the relay is good?
  3. Tried blade forums but although it seems to be a common problem, no one has a solution. Or at least one they'll share.

    Swapped the relays over and the same thing happens. Also ran power through it and it clicks on/off (open/closed).
  4. Ravers

    Ravers LE Reviewer Book Reviewer

    I'm not too sure about bikes but I had a car with the same problem a few years back (Lancia Kappa Coupe, Alfa 3 litre V6 lump). The RAC man got into the boot and twatted the floor above where the fuel pump was located with a lump hammer while I turned the engine over.

    It worked. Try giving your fuel pump a decent clout, might sort it.
  5. Can't help with the problem, but stop doing that. It's like turning your computer off by yanking the extension socket out of the wall.
    • Like Like x 1
  6. If there is a fault on the ignition system then when you turn the bike on the earth could be live. This could effectively put a ghost fault in the pump as the earth wire will be carrying voltage. 12v at both ends-instead of 12v in, through the component and earth out. Look at a wireing diagram and see if the ignition relay shares a common earth with another component.
  7. Grumblegrunt

    Grumblegrunt LE Book Reviewer

    have you been all over it cleaning the contacts, 10 year old bikes generally start going green. most of the fuel pump issues I come across are due to bad contacts not letting enough current through.

    you could patch it through an ignition live or a switch and run it like that for a bit.
    • Like Like x 1
  8. DM,

    That close-down is a whole other debate! I have been told not to use the killswitch by about eaqual numbers of mechanics who have told me to use the kill switch. Either way , kill-switch or key, the basic effect is the same. Its like having a computer with the option to switch the plug socket off at the wall or pull the plug out of the socket. There is no "soft" close down routine.

    I have known GGs answer to be the case in a number of confusing electrical quandries - power getting through enough to register on a meter and fool you into thinking the circuit is good but just not quite enough or reliably enough for correct functioning of whatever it may be.
  9. How do you know the battery is good? Is it holding a charge? Out a meter over it, and turn the ignition, see what the battery drops to.

    Sent from my Desire HD
  10. There is a box on the bike that cuts the engine when it crashes/falls over. This went on my GSXR750 and gave the exact same symptoms. Can't for the life of me think what it's called though. I replaced it with one off eBlag and it did the trick!
  11. It's called a tip over sensor!
  12. You could try a test lamp. It draws current and will indicate as an open circuit under those circumstances..
  13. That's a BAS (bank angle sensor) on a Honda.