fuel pump

Discussion in 'Yamaha 250cc In-Line 4's' started by frostychris, Mar 23, 2009.

  1. frostychris

    frostychris New Member

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    was wondering how to find out if my fuel pump is the reason why my bike wont start
     
  2. dontz125

    dontz125 Active Member

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    Dismount / bypass the pump, fill the tank past half-full (or lift the tank up so the bottom is above the carbs). See if it starts...
     
  3. dave

    dave Well-Known Member

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    Open one of the carb drain valves. If fuel keeps running out and you get more than 1/2 a cup then it's not a problem. Just don't be smoking or light a match.
     
  4. frostychris

    frostychris New Member

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    alright,

    so i tested it out, pump, pumps fuel, makes a funny noise then stops,

    i also tryed strating with out the fuel pump, ie holding the tank up and and the bike still didn't start any ideas?
     
  5. dave

    dave Well-Known Member

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    Ok, I suspect that the pumps stops if the engine is not running as they all do that when you first turn on the ignition. If you have spark at your plugs and the compression test is ok (over 100psi) then it must be a fuel problem.

    Try squirting some fuel (or "start ya bastard")down the throats of the carbs and see if it goes for a short period. If so it is being starved of fuel. I started an old xr100? by soaking the sponge air filter in petrol and it ran for about 30 seconds.
     
  6. frostychris

    frostychris New Member

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    how do i find out if i have spark at the plugs, another mate said that might be the problem
     
  7. dontz125

    dontz125 Active Member

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    Take a loose (reasonably clean) plug; unplug your #1 spark wire, connect to the loose plug. Lay plug on cyl head, crank engine - watch pretty blue sparks (works best in dim area, full sun not so good).

    Lather, rinse, repeat.

    Be VERY sure the plug stays in contact with the head; I don't know about these beasts, but some ECUs have this annoying habit of frying themselves when operated without a connected plug at the business end. (These are TCI, not CDI, so they should be safe. I'd rather not gamble on someone else's black box, though...)
     
  8. frostychris

    frostychris New Member

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    alright tested all plugs, they all spark, so what else could it be?

    fuel pump works, spark plugs work, start the bike and just hear the i don't know how to dicribe it, sounds like its trying to start just doesn't have the vrooom... <!-- s:( --><img src="{SMILIES_PATH}/icon_sad.gif" alt=":(" title="Sad" /><!-- s:( -->

    so the ECU should be fine if the spark plugs work?
     
  9. dontz125

    dontz125 Active Member

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    Have you checked your valve clearances? These things like to settle their valves into the head, especially the intakes. Tight valves = leaking = no compression. The whole FZR family is notorious for hard starting caused by too-close valve clearances.
     
  10. frostychris

    frostychris New Member

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    how do i find this out?
    how do i get to the valves?
     
  11. deadbirds

    deadbirds New Member

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    wow.
    thats been around a bit.
    looks a bit past it...
    the rust on the swingarm dosnt look very healthy..
     
  12. frostychris

    frostychris New Member

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    yeah its has, was just surface rust came straight off with a lil bit of sand paper and some WD40
     

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