back fires and vapor lock?

Discussion in 'Sportster Models' started by dick fitz, May 28, 2008.

  1. dick fitz

    dick fitz New Member

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    I need a little help... I ride a 2003 custom 1200XL that has about 7500 mi on it. Three weeks ago it started to have problems. After a cold start, about 5 miles out, it back fires then about a mile later stalls. The stall feels like a varor lock. I cannot start it right after the stall but If I wait for 10 - 15 minutes it starts right up and I won't have a problem for the rest of the ride (well not yet). any thoughts on the cause / fix??
     
  2. R. Lewis

    R. Lewis Senior Member Retired Moderators

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    How long do you let the scoot warm-up before taking out,do you ride it every day,have you had any work done on it lately,fuel octane???????
     
  3. dick fitz

    dick fitz New Member

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    I warm it up for about 2 miles ~5min. I ride 1 - 2 times a week. the strange thing is after the stall it runs fine. I have noticed a little oil around the carb that could be a problem but I don't understand the stall.

    No hiss when I remove the cap. The last two times I went out I kept the cap loose to see if that would help... same problem.
     
  4. R. Lewis

    R. Lewis Senior Member Retired Moderators

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    have you had any mods. done?? How far of a ride do you do the 1-2 X's a week?
     
  5. glider

    glider Veteran Member

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    Try this just on a chance. Open this screw about 1 1/2 turns with the petcock open and let a few ounces of fuel flow out then close it again. Repeat it a few times.

    Look through from the opposite side of the carb and you should see this screw assuming that it's a carbed bike.

    [​IMG]
     
  6. dick fitz

    dick fitz New Member

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    R. Lewis, I run 93 octane.

    No modifications on the bike... Thats the wierd part. When I ride I'll go 50 - 100 mi. after the inititial stall it runs fine for the rest of the ride.

    Hobbit, Last time I rode I loosened the gas cap, real loose it rattled but did not let the gas spill. same problem backfire / stall. 10 - 15 minutes later started it up like nothing was wrong and had no problems for the rest of the ride.

    Glider, I do have a carb. I'll try your suggestion and let you know what happens.
     
  7. dick fitz

    dick fitz New Member

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    Group, thanks for the suggestions... Last weekend I took Jaystronghawk suggestion and pulled the CPS (Crank Position Sensor). the 2003 has a cam shaft... same thing different name. This computer stuff will drive you nuts. anyway, before I pulled the CPS I disconnected the batery cables, as instructed in the manuel, and found that one of the small cables (blue) was disconnected. The CPS looked fine, the area was clean end all of the screws / bolts were tight so I put the thing back together (making sure all of the cables were connected to the battery and went out...

    Three rides so far and no backfires or stalls. If this happens to you, do the simple stuff first

    check the battery connections
    Check your filters
    Make sure your petco** (sounds like my wifes nickname for me) vent hose is not crimped
    pay attention to your gascap vent

    If all fails bring it to the dealer to see "if it's throwing codes" (I hate this computer stuff)