1985 VF500F Fuel Pump

Discussion in '1st & 2nd Generation 1983-1989' started by srashid, Apr 27, 2013.

  1. srashid

    srashid New Member

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    I have a 1985 VF500F that I bought new. I may have a fuel pump problem, but I've been told that the fuel pump for this machine is no longer available. Does anyone have a good substitute fuel pump in case it turns out I need one. I replaced the pump once before, about 6-7 years ago, and that corrected a similar problem I was having at that time. Thanks.

    - Steve R.
     
  2. commrad

    commrad New Member

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    mine has a MR Gasket #42S universal on and it works fine.
     
  3. srashid

    srashid New Member

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    Thanks, Commrad, I'll try that.
     
  4. commrad

    commrad New Member

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    It'll also work fine with no pump. I've seen several people around who have ditched the pump and went to gravity feed.
     
  5. Metallican525

    Metallican525 New Member

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    My wife's 500 is gravity fed now after having stalling problems with hers. Runs great, not a problem since I yanked it out!
     
  6. Porkchop

    Porkchop New Member

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    My 84 never had a fuel pump. I had lines run 2 different ways and never had a problem with gravity feed on either routing.
     
  7. tinkerinWstuff

    tinkerinWstuff Administrator Staff Member

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    Agreed with what's already posted; well documented that the 500 runs great gravity fed.
     
  8. squirrelman

    squirrelman Member

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    Don't blame a pump until you've tried bypassing the failure-prone pump relay.
     
  9. Belgarion

    Belgarion New Member

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    More information about bypassing the relay?
     
  10. Metallican525

    Metallican525 New Member

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    I don't have the wiring in front of me but I would imagine you could find the two largest wires and conect them thereby defeating the relay and turning the pump on all the time. You would then need a switch to keep from killing the battery tho. Often times relays are used to carry the load of the circuit you can use smaller gauge trigger wire so I would look into getting a universal 4 pin relay from a local auto parts store and replacing it instead of "hotwiring" the circuit.
     
  11. creaky

    creaky New Member

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    To test the fuel pump.......Run the engine for a couple of minutes. Turn off the engine, pinch the vacuum line to the petcock shut, turn the petcock off. Disconnect the out fuel line from the pump and have a container handy to catch the gas. Pull the plug off the pump relay, insert a jumper wire between the black and white wires. Turn the key on, if the pump runs, let it flow fuel for 10 seconds, the pump should deliver about 600-700 cc.
     
  12. squirrelman

    squirrelman Member

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    Not quite correct, sir ! After the 2 wires going to the relay are connected at the plug, the pump is powered ONLY when the key is ON, so no need for extra relays or switches.
     
  13. Belgarion

    Belgarion New Member

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    How does the pump not flood the bowls anyway? There's no fuel return line. I'm coming from an automotive electronic fuel injection background so I realize I don't have a good concept of how carburetors and fuel pumps work. It just looks (with my limited knowledge) as though the pump will flood the bows or the cylinders and the motor will die. Also, if the pump is running when the motor isn't running isn't that a problem? Wouldn't be in a system with a fuel return and EFI, but VF500's have neither EFI nor fuel return lines.
     
  14. Metallican525

    Metallican525 New Member

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    Good point sir. As I said I didn't have the wiring in front of me at the moment. If you hooked it up correctly/incorrectly depending on how you'd like to look at it you could have it run all the time if you used the 12v wire instead of the relay trigger wire. Trigger wires are usually smaller low load applications hence the relay. In any case, good correction/clarification of my :boozer: rambling!!!
     
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