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Thread: Scratching my head poor running bike

  1. #1
    Junior Member
    Join Date
    Jun 2021

    Scratching my head poor running bike

    Hello from Arizona. I am new to the world of Buells! I have had my eye on one for a while and finally pulled the plug. Long story short I purchased a 2000 Lighting w/ 13K has aftermarket intake and Vance Hines Exhaust from a guy locally. The PO told me he was having issues getting the bike to run correctly and has been to a shop in Flagstaff, AZ multiple times. Now for the issues, at 1/4-1/2 throttle runs fine till about 2500 RPMs then starts to bog down, spits and sputters, and few backfires, and eventually, the bike will die. According to the paperwork the shop replaced: O2 sensor, temp sensor, new plugs wires and spark plugs, new intake gaskets, fuel filter, and a new coil. The final time he brought the bike in they told him it needed a new fuel pump. I thought no big deal I can easily do that. Before I toss more parts on it I was wanted to get some feedback. Any help would be awesome!!!!!!!

    I have checked all of the following since it seemed like the shop wasn't too sure of the actual issue and just tossed parts at the bike.

    When the bike is first turned on the fuel pump primes and sits at 50psi then drops to 0 (is this normal?)
    Fuel Pressure on startup is 50ish psi (I tested the fuel pump using ECMSpy and got the following error: Failed to Finish active test: Checksum Error. What does this error mean, is this considered a failed test?
    I haven't been able to test the fuel pressure while riding the motorcycle
    Reset TPS sensor
    Cleaned throttle body
    Cleaned and test the injectors and they spray a nice clean stream with no leaking
    Tested for air intake leaks and I don't hear the engine increase RPMs when starter fluid or similar fluid is sprayed
    All wires are intact and no wires have been worn through
    Check engine light that came on twice was for the temp head sensor (keep in mind a new one has been installed and that is the only code I have seen pop up in over 2 months)
    The AFV is at 150% for both front and rear and the EGO Corr % is also at 150% for both front and rear (I just installed ECMDroid and will try and reset the AFV)

  2. #2
    Senior Member Cooter's Avatar
    Join Date
    Dec 2012
    Crawling up your skirt
    Thank you for the clear information you provided because "Your answer can only be as good as your question"

    I'm not one for replacing parts that I can't prove are bad, but considering your situation, I'd put $ on a fuel pressure or volume issue. Looks like everything else was checked and/or replaced. Bad pump, clogged fuel filter/sock, perforated fuel line in the tank, etc. PM Barrett on here for a quality re-build kit or whole assembly.

    Both your AFV and EGO are telling you the ECM is desperately trying to add enough fuel to run correctly. The fuel map/ECM isn't the issue.
    Last edited by Cooter; 08-21-2021 at 03:59 AM.

  3. #3
    Senior Member Endopotential's Avatar
    Join Date
    Jan 2018
    Just call me 32:16 from now on
    Ditto on the fuel pump. It's 20 years old now.

    My '07 with half your miles would take forever to start up. As Cooter said, the curvy hose that's a part of the fuel pump system had developed a pinpoint hole. That whole system sits submerged in the main tank. So no external gas leak outside, but the system just couldn't maintain adequate pressure. That could just explain the symptoms you list.

  4. #4
    Senior Member Barrett's Avatar
    Join Date
    Jun 2020
    AmishLand, PA
    Sir: Unless an unknown dealership is sitting on a NIB tube-framed Buell complete pump assembly and has purged the info from the system...ALL pumps now NLA. Most all factory issued repair parts now NLA. All your indicators point to a failing pump assembly to include back-firing thru air intake side of engine...obscenely high AFV values....horrible throttle response. Tube-framed Buells have a nicely designed and easily accessible pump, as opposed to XB models which possess an overly complex and difficult-to-access pump. Remove yours and refresh it. And to answer your question....YES on your pump characteristics. Key and kill switch to ON has pump charge system, then pressure drops to 0. Pump then resumes pressurization when ECM sees CPS pulses...12V is sourced....ECM completes circuitry by supplying ground.
    Closely check pump motor attachment strap. If questionable, replace with improvised part. If it fails, the motor will instantly rotate destroying the sealing washer and wiring harness rendering the pump garbage.


    WALBRO 521
    AC DELCO-- - EP274
    DELPHI--- 25337782 OR FE0052
    FORD-- E5ZZ-9A407-A


    Good luck.

  5. #5
    Senior Member pdksh's Avatar
    Join Date
    Nov 2016
    Thank You for the shopping list of parts Barrett!

    Gotta love cross reference part numbers

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