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749 - Fuel Pump Not Priming

Discussion in 'Technical Help' started by RickyX, Sep 3, 2020.

  1. Had another go at this today.

    Fully charged battery
    New relay
    Swapped the entire front (race) loom for a brand new, never used one
    Took battery box off
    Took ecu out and cleaned all connectors, emeried the earth lead, nut,bolt and reconnected.
    Swapped the ignition aerial with my other one (known to be ok)
    Checked all wires around battery box and relay for signs of chaffing or damage - nothing found
    Rechecked all fuses, all ok
    Disconnected fuel pump and checked plug etc all ok

    Switched on and still no fuel pump prime.
    I can hear the relay clicking each time it is powered on.
    Error code 37.3 still.
    No amber light on dash, just a constant alternating of the “code” and temperature readout.

    I wiggled all wires while the power was on, behind battery, around ecu, at pump, into clocks, every-fuckin-where...dead as a dead thing.

  2. Including the 3 amp fuse for ECU on battery box?
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  3. i have had a hairline crack in ecu fuse cause loads of inexplicable grief and 37.2 errors
    also maybe check your side stand switch (or the quality of the bypass)
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  4. Yep. Checked.
  5. Yep. Checked the bypass and also used a bit of lock wire across terminals.
  6. Hi,
    my 999 left me stranded once. Engine just went out. Pump didn't prime...Waited a while...Tried again, pump primed, bike died after a minute running...pump didn't prime...and so on. The fault was a broken cable in the aluminium housing that goes into the pump. Its not visible as it filled with epoxy, but the pump didn't get power because of that broken cable.
    You can either repair it, but you have to use fuel resistent epoxy ... or buy a repair kit.

    Good luck!

    IMG_0390.jpeg IMG_0371.jpeg
    #26 virtualcowboy, Sep 12, 2020
    Last edited: Sep 13, 2020
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  7. Thanks guys.
    My next course of action was going to be to swap tanks between the road and track bikes.
    The strange thing is, when I was at Brands and it conked out on track, when I got back to the pits it did start and run again. Subsequently it wouldn’t restart.
    Sounds like a dicky wire/connection.
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  8. Swapped tanks today - road bike onto (broken) trackbike....

    Drum roll.............

    Freakin works!!!!!

    So, it is the fuel pump.

    Will have a look for one of those repair kits that @virtualcowboy mentioned.
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  9. Great! Happy that I could help. I took me a lot of headaches to find the fault...
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  10. you have almost earnt your cigar Andreas, but can't rule out the pump itself failing yet.. but provisionally:-


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  11. When you find the kit Please post up, as it seems like a spares stash essential :upyeah:
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  12. Initail look at @virtualcowboy linked part appears that there is no need to dig out resin etc and reseal the wires as it appears to be a complete assembly, plug and play type.
    Can you confirm @virtualcowboy ? Also, is it correct for a 749 fitment? Cheers.
  13. With this kit you just have to exchange the part. The ressin epoxy is only needed when you decide to repair the part on your own. Having done both myself I would choose the replacement part.
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  14. Took a punt and ordered the 51020032A.
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  15. I had exactly this problem, the wire breaks where it flexes at the point where it enters the resin. The insulation remains intact though, so not obvious on examination and can be an intermittent fault.
    The clue is that the fuel pressure reduces slowly, so when the engine dies it does so softly.
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  16. Something for the weekend, sir?

  17. dont know what you were faffing about at..... it'll be the wires that are inside the fuel tank on the pump!
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  18. I thought that this includes those wires...haven’t looked at a fuel pump for a while.
    Time will tell.
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