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Intermittent Petcock failure

Discussion in 'XJ Technical Chat' started by dubyaohohdee, Jun 25, 2012.

  1. dubyaohohdee

    dubyaohohdee Member

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    Twice now in the last month the petcock has gone dead while riding. Both occurred at 10-20 miles out. Bike dies, I change to prime and wait 30 seconds and we are back in business. Last time I thought I had caught it early enough, but the bike still died after about 10 seconds even on prime.

    I have a clear fuel line on at the moment and have it routed so that I can see the fuel flow thru the line for confirmation.

    Rebuild kit i guess?

    Also, does the xj650 petcock fit on an xj750 tank?
     
    dubyaohohdee, Jun 25, 2012
    #1
  2. bkerby

    bkerby Member

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    you didnt by chance put on clear vacuum line instead of fuel rated hose? The clear vac line will colapse under heat and pressure and restrict fuel flow.
     
    bkerby, Jun 25, 2012
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  3. dubyaohohdee

    dubyaohohdee Member

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    It is clear "yard & garden" fuel line. I intend on replacing, but I had it installed for other troubleshooting activities. I dont believe it is the issue as the bike runs fine after 30 seconds rest.
     
    dubyaohohdee, Jun 25, 2012
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  4. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    It very well could be, and you'd never see it happen.
     
    bigfitz52, Jun 25, 2012
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  5. DuoDS

    DuoDS Member

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    Also, make sure your gas cap is venting properly. If the cap does not let air into the tank, it will produce a vacuum that prevents proper fuel flow. My son's XS has this problem.
     
    DuoDS, Jun 25, 2012
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  6. dubyaohohdee

    dubyaohohdee Member

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    Hmm, hadnt thought of the gas cap. How does one check the cap?
     
    dubyaohohdee, Jun 25, 2012
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  7. DuoDS

    DuoDS Member

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    Ride until it stops running, pull over and pop the gas cap. LISTEN!! if you hear a sucking sound, you have created a vacuum and know your gas cap is not venting properly.
     
    DuoDS, Jun 25, 2012
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  8. ifonly2005

    ifonly2005 Member

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    i got an 80 650 with same issues... seems legit to me. ive routed it down to vaccuum. if i pull the fuel line off and crank, she will fire back up. (hence letting air back into the system out of "vapor lock" you guys have any suggestions on cleaning caps? figured i would clean the cap and replace the vaccuum line just for giggles.....
     
    ifonly2005, Jun 26, 2012
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  9. adrian1

    adrian1 Active Member

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    adrian1, Jun 26, 2012
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  10. RickCoMatic

    RickCoMatic Well-Known Member

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    Replace the Garden Variety Hose with Certified Vacuum Line.

    I've seen all too many cases of guys replacing that Vacuum Line with the Hose that comes along with a New Battery.

    Once the Vinyl gets warmed-up enough by the Engine Head, ... the Manifold Vacuum collapses the Hose.
    That, closes the Petcock Valve.

    If, like you say ... switching to PRI alleviates the condition and you're up-and-running again ...

    Swap-out the Hose for Vacuum Line before you get too far into looking for why the Engine Stalls.

    You can get Vacuum Line at an Auto Parts Store for about a Dollar per foot.
     
    RickCoMatic, Jun 26, 2012
    #10

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