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XJ 700 petcock fuel leak

Discussion in 'XJ Technical Chat' started by ddanielf, Apr 24, 2022.

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  1. ddanielf

    ddanielf Member

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    Hey all! My Xj 700 was leaking fuel that ended up dripping all the way to the back wheel.
    I've noticed that it was coming from the petcock. It seems like the leakage comes from the part that is connected to the tank (see photos), given the damage it did to my tank.

    Do you guys think I should replace the rubber seal or apply some rtv?


    Thanks!
     
  2. bensalf

    bensalf Well-Known Member

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    yes replace the rubber seal, you would have to take the tap off anyway
     
  3. ddanielf

    ddanielf Member

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    The seal looks very old, so I'll just replace it.
    But one thing I've noticed when removing the tank, was that the petcock did not hold in the fuel. As if the vacuum system was not working. Big mess.
    Could the vacuum hose be also faulty? or is it because there was air leaking from the seal part?
     
  4. Huntchuks

    Huntchuks Well-Known Member

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    It is not a fault with the vacuum hose. If there was no vacuum you would have no fuel flow. It looks like you need to replace the diaphragm and other parts in the petcock after you take it apart to inspect and clean.
     
  5. bensalf

    bensalf Well-Known Member

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    theres a HOW-TO write-up on here if you do a search, to renovate the petcock, the diaphragm may be ok ,it could just be the valve seat needs refurbishing, but if it needs a diaphragm , theres usually a new petcock to tank seal in the kit anyway
     
  6. Huntchuks

    Huntchuks Well-Known Member

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  7. ddanielf

    ddanielf Member

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  8. ddanielf

    ddanielf Member

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    Update: I've replaced the o-ring and the 2 washers. And that seems to have fixed the problem. No more leaking. Didn't need to redo the petcock.
     

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