Engine cuts out at idle when warmed up

Discussion in 'Engine, Fuel and Exhaust' started by mark_bert, Oct 22, 2008.

  1. mark_bert

    mark_bert Member

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    hi all,

    I have a 2005 FLTRI that doesn't like to idle once it's warmed up. Here's the particulars:

    Idle is right about 1050 rpm once warmed up.
    It will intermittently drop to about 400 rpm, sometimes will recover, usually will die.
    Runs fine once it's over about 1200 rpm.
    If I hold the throttle at about 1200 rpm, it will run fine.
    SE high flow A/C.
    V&H slip-ons.
    V&H FuelPak.

    My thought was that it might be one particular cylinder that's causing the issue. Here's the odd part. If I pull a plug wire, either plug wire, doesn't matter which, idle drops to about 900 rpm and it doesn't miss a beat. Put the plug wire back on, idle pops back up to about 1050 rpm and the stumble comes back.

    I'm not sure where to go from here (other than to a real mechanic). It acts like it's starved for fuel at idle. I thought maybe one of the injectors was cutting out once it got warm but since pulling one plug wire should have isolated one injector or the other didn't work, I'm not sure.

    Any suggestions are welcome.

    Thanks,

    Mark B
     
  2. glider

    glider Veteran Member

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  3. mark_bert

    mark_bert Member

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    No trouble codes triggered.

    Also, I disconnected the FuelPak from the system to see if that might be the issue and it made no difference.

    I saw the thread on fuel lines inside the tank and although fuel level does not affect this, is it possible a hole might exist that would affect low volume vs. high volume fuel flow? Does the fuel pressure vary with demand or is is constant?
     
  4. glider

    glider Veteran Member

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    Fuel pressure should be constant, just below 50lbs and the hole in the line could effect this and give you erratic running possibly like you have.
     
  5. mark_bert

    mark_bert Member

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    It might be a while before I get the chance to open the tank and look inside. But I plan on checking the hoses in there.

    On another note, from another suggestion, I went ahead and cleaned up the throttle body to get out any build up in there. I ran it with the a/c off and noticed that when it dies, it's actually backfiring a bit back up the throat of the throttle body.
     
  6. glider

    glider Veteran Member

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    Mark

    Put your bike year and model in your profile to make it easier on anyone responding. Use the User CP up top on the left.

    If it's backfiring through the intake, take a compression test to check the condition if the valves.
     
  7. mark_bert

    mark_bert Member

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    I've think I may be on to something... I checked the TPS voltage and it's reading .55vdc with the engine off and jumps up to .60vdc with the engine running. Any info I've been able to find says that it should be .51vdc running or not with the throttle closed. Does this sound correct? Is the TPS adjustable or do I need to replace it? Anyone have a part # for a new TPS?

    Thanks A Lot,

    Mark B
     
  8. glider

    glider Veteran Member

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    The .51 sounds about right for that bike but the .55 wouldn't cause the problem you are having I don't think. They are not adjustable like the older units on the morelli bikes.

    Are you running any tuner like the PC III that would require the setting of the TPS during setup?
     
  9. mark_bert

    mark_bert Member

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    It has a V&H FuelPak. There is a step there where it sets the throttle position. But since it shows the same symptoms if I disconnect the FuelPak, that's out. Also, the V&H tech guy said that the FuelPak doesn't operate at idle anyway.

    Back to the drawing board.
     
  10. glider

    glider Veteran Member

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    Take a look at the idle stop screw in the lower right of the throttle body to see if it is missing or moved, even uncapped like someone messed with it. If it backs out on it's own, the idle actuator motor will take over but not as it should to keep the idle speed constant.

    Capped in pic on right, uncapped on left.

    [​IMG]