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Thread: BAD ECM

  1. #11
    Site Supporter T_C's Avatar
    2005 St1300
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    Mar 2012
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    Re: BAD ECM

    Quote Originally Posted by jspano01 View Post
    I’m running out of things to check.

    Check for another STowner int he area. But them a burger and a beer and borrow an ECM.
    1 drop in reverse, so is that a minus 1? 205/50-17 Goodyear TripleTred, 130/70-18 Bridgestone BT-45 (rear)
    While you're alive, shine: never let your mood decline. We've a brief span of life to spend: Time necessitates an end.

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  3. #12

    Re: BAD ECM

    Here is just something to think about, if something on your bike caused damage to the ECM, would it not be possible that it may damage a borrowed ECM as well?
    A burger and beer may not be enough to make someone happy if you toast their ECM by accident. Just putting this out there.

  4. #13
    jspano01's Avatar
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    Macedon NY
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    Re: BAD ECM


    I agree. I wouldn't feel comfortable using another members ECM. Would be happy to offer mine to test in another bike to confirm the same failure mode.

    Some amusing history.
    First failure on the bike was two weeks ago running at 60 mph the bike just quit as if the engine run switch was turned off. Cant remember what displays lights did or didnt come on but it just die. Pulled over and found the bike would crank but not start not even pop ,nothing except crank. Waited 1/2 hour and the bike would start again and run maybe another 30 miles. Of course I didn't have tools a meter or schematics at that time its a Honda no need to right?

    That night pulled a fault code that indicated the crank shaft position in sensor was bad , I recall a few days of stuttering during idle and rough running so I replaced it and on the next ride same thing, thirty miles into ride bike just quit. ( full tank of gas ) This time I was prepared discovered two ignition wires from the ECM to the coils had the insulation rubbed off. I found this by dumb luck. It appears the tool bag was the culprit. Couldn't find any metal to metal contact so taped the wires waited 1/2 hour drove the bike home and tore into the rear cowl the next morning. Checked all the ECM relays and wires for more damage corrosion found nothing , repaired the coil wires figured I got it licked this time!

    Made the mistake of driving to a local water hole famous for hosting those guys that look like pirates on big loud V twins. Had my beer told some motorcycle lies and as luck would have it when I went to start the bike ..nothing but cranking noise followed by the obligatory explosion of laughter from the peanut gallery observing my misfortune.
    Fifteen minutes later with the fuel cut out relay jumped the bike was running. Tail between my legs I drove home.. or attempted to! I got ten miles on a twenty mile return trip and the bike quit again. This time the fuel pump refused to run. Wife picked me up with the trailer I left connected to my car just in case I break down.
    All the way home she gave me that you dumb **** smirk it was not a good day for me or the Honda. Next morning removed the pump put 12 volts across the +/- terminals and it wont budge not even with a dental pick prying the rotor . One warranty fuel pump later I figured its got be the pump right? I mean its prime riding season and I paid my dues in front of those Harley guys the world cant be this cruel.

    This leads me to where I am today .
    Fourth pin in on Black ECM connector the brown and black wire from the fuel cut out relay coil to the ECM does not ground. I figure the coil wire thing probably damaged the ECM
    As far as the fuel pump failing well its a Quantum high flow that replaced last year at this time and since it was replaced under warranty I wont complain about it being fabricated from chi-nee zium inexpensive metal with a half- life inversely proportional to the criticality of the component its used on.

    As luck would have it the Quantum customer service group folks double shipped .. I got two pumps for free. Thanks guys  What are the odds Partzilla will follow suite and double ship an ECM order?

    For the record I have 62K flaw free miles on this awesome bike its about due for some parts

  5. #14
    drtyrrel's Avatar
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    Re: BAD ECM

    Last year the crank shaft position in sensor went bad on my BMW r1100rt. I was driving home on the highway in a down pour and it just died. I coasted down an exit ramp. I waited 5 minutes and it started back up. Drove 10 miles died again so on until I got home. Next day it ran fine (no rain). Ended up finding the insulation on the wires to the sensor got crispy and fell off.

  6. #15

    Re: BAD ECM

    Maybe they sent you two quantum high flow pumps because they know they fail and they sent you a spare just in case? I have no experience with aftermarket pumps, as I recommend OEM parts for stuff like that.
    I would start looking around the fuel pump and or under the fuel tank to see if you pinched a line, disturbed a ground wire, or blocked a vent line or hose first.
    I would also go to the front of the bike and check the crankshaft position sensor switch. These wires will be routed back on the left side of the engine (as seated on bike) and run right next to the exhaust system.
    Its possible you have a cooked or damaged wire to this switch.
    I would then check some or all of the following: pinched or clogged fuel hose, faulty fuel pump, clogged fuel filter, clogged fuel injector filter, sticking fuel injector needle, faulty or disconnected camshaft position (CMP) sensor, the crankshaft position (CKP) Sensor as stated above, and really look at a faulty fuel pump even though you replaced it (since its not a honda part).
    When was the last time you did a TB sync? Your starter valve synchronization may be misadjusted, or the lines/5 way tee may be clogged.

  7. #16
    jmcarruth's Avatar
    2003 ST1300 ABS
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    Re: BAD ECM

    What year ST? Some 2003s had grounding and wiring harness issues and were recalled. Mine was one of them.
    The first thing I would check after a load test on the battery is that all connections and grounds are clean and tight, then move on to all fuses, plugs, then relays.

    John Carruth, STOC #375
    2003 ST1300 ABS, 2011 KLR 650
    2012 Monster 1100 EVO, 2017 Harley Road Glide Special

  8. #17
    Be Thou My Vision dduelin's Avatar
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    Re: BAD ECM

    With the key ON do all of the lights in the front half of the bike operate normally including headlights, position lights, turn signals, horn, and instrument panel backlighting?

    The ST is prone to ground circuit problems that can cause the fuel pump not to run, it's not an uncommon problem that manifests itself in various ways usually through some strange behavior in these circuits but not always. All the grounds (green wires on your Honda) in the front half of the bike including the fuel pump run through a small yellow bus bar behind the RH headlight and then through a white plastic 24 pin connector outboard of the left side frame above the left valve cover. Uncover the 24 pin connector and fashion a jumper wire to provide an alternate ground from the forward side of this connector's green wire directly to the frame. If the fuel pump spins up you are good to fashion a permanent ground repair.

    My bike had lighting clues that came and went without engine run issues but eventually the fuel pump cut out and the bike would not start until the ground issue was resolved.


    Honda ST1300
    Honda NC700XD
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