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Thread: 2008 XB12XT - Occasional sputtering and loss of throttle pulling away in 1st gear

  1. #1
    Junior Member
    Join Date
    Oct 2019

    2008 XB12XT - Occasional sputtering and loss of throttle pulling away in 1st gear

    Hello Forum,

    I am located in Halifax, Nova Scotia, Canada and new to this forum. I own a stock 2008 XB12XT with 25,000km (15,000 miles). The last 2 summers I have been experiencing - on occasion - a sputtering, loud puffing and loss of throttle when pulling away in 1st gear. By occasional I mean it happens say 1 out of every 3-4 rides. My response to this issue is to rev the bike (cutch in) high and then slowly release the clutch. Most times it will labour itself enough to get into second gear where it runs smoothly. In fact, it runs smoothly in all other gears at all other times.

    I had a scare this summer where it sputtered, puffed and I lost the throttle power while trying to pull back onto a busy highway.

    It feels and sounds like it is about to conk out or stall, so I rev the throttle high and try to pull away. This issue happens when the engine is cold (1 minute warm up idle) and when the bike warmed up after a ride.

    This issue has me perplexed. I took it to my local Harley dealer and $300 buck later, they said o2 sensor "may" be cause (diagnostic) but they were not sure. Every time I have it looked at the bike behaves normally. Very frustrating.

    Any advice would be greatly appreciated. I have some basic mechanical skills, but I would not be able to remove the fuel pump for example.

    Thanks to all in advance.


  2. #2
    Join Date
    Feb 2011
    AmishLand, PA.
    dino: the short check list on your 2008 as follows: is the rubber nipple/cap installed on the throttle body(TB) vacuum port? is the rubber air boot correctly attached to both the TB and the airbox base plate? do you have any historical fault codes stored in the ECM?
    if you've been running any sort of ethanol blend gasoline then in all likelihood you have a failing fuel pump. your signs and symptoms point towards same.
    any sort of after-fire out the exhaust and/or symptoms that mimic the kill switch being turned off and on is always ignition/spark related.
    any sort of back-fire/chuffing/puffing into the intake tract is always fuel delivery related.
    only you can determine exactly which symptoms seem the most exacting.
    Last edited by user_deleted; 10-03-2019 at 12:35 PM.

  3. #3
    Junior Member
    Join Date
    Oct 2019
    Lunatic, Thank you for your reply. I really appreciate it. I will check all and get back with an update. If it is a failing fuel pump, do you know if replacement pumps are available? Dino

  4. #4
    Senior Member Cooter's Avatar
    Join Date
    Dec 2012
    Crawling up your skirt
    Yes, fuel pumps are available. The guy recommending one has a bunch, and sells them very reasonably to fellow Buellers The replacement is actually very easy with basic tools, and an A-frame ladder (seriously). Check out or for a free .pdf download of the service manual. Supporting the rear of the bike and disconnecting the lower shock bolt will let the pump come out without taking off the swing arm

    As reasonable as fuel pumps are... you may want to actually diagnose the problem and replace whatever part that actually tests bad. IMO.

    I would start by getting a good diagnostic tool. ECMDroid is free on Google Play and will communicate to your ECM through a wireless Bluetooth connection. You'll need a Bluetooth dongle to plug into the bike. I like mine from

    The free ECMDroid app can read codes, change ECM settings, load different fuel mapping, and test all the sensors on the bike. It can even see if the ECM is compensating for the bike running rich or lean (AFV) to get you closer to knowing what the problem is, instead of guessing. IMO.

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