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Thread: yamaha superjet total loss

  1. #1
    D-Roc Guest

    Default yamaha superjet total loss

    i recently installed the latest msd digital total loss ignition on my yamaha superjet. I had JSS make a backing plate and wire everything up. This was my third install of these units and it was a snap with the work John did with the wiring. I set the timing and curve. Checked for spark on appropiate cylinders. i poured gas down the carbs a few times to light it up to check that it would fire and it did. today i flushed my tank and fueled it up, primed the lines and fired it up. ran awesome for 30 - 45 seconds and quit as if i hit the kill switch. now when i crank it over it will crank about 2 revolutions and then spark each plug once and that is it. red led is blinking. any ideas of what to check for? is it not picking up the signal from the pickups? Any input would help. Thanks.

  2. #2
    D-Roc Guest

    Default testing

    okay, so i put the brain in test mode and rotated the flywheel and the LED lit up twice. I am guessing that the pickups are okay. Then i switched back to run mode and jumped the pickup wires and can fire the rear cylinder. The front cylinder will only spark once and then it just blinks the LED every time i jump the wire. if i turn the switch off and then on it will fire the plug once. i swapped spark plug wires and had the same result. i was thinking of switching the brown and yellow wires from the brain to the coil to see if i can fire the "bad coil" on the other circuit to determine if it is the coil or the brain. is this okay to do? i don't see the problem with fooling the brain on which coil it is to fire. I can borrow a coil but everything is professionally wired and heat shrunk. i don't want to tear into it if i don't have to.

  3. #3

    Default 42351

    You can swap the coil to a different channel to determine whether it is bad or not. The 42351 is a three channel ignition so you also have a spare channel on a two cylinder application if one channel happens to go out. A few things to check for if you haven't already: On the coils is the right hand side of the coils grounded ( tower facing up as a reference)? Is battery voltage good? Sometimes voltage will be okay but the amps will not be sufficient enough to fire the ignition. Have you checked the air gap between the magnet in the flywheel and the pickups. You may get an led during slow cranking but lose the signal once a higher RPM is reached. Thanks,Bret- MSD Powersports Tech

  4. #4
    D-Roc Guest


    Bret, i have my coils mounted on a epoxie board mount. it Doesn't ground the coils on both sides. i figured that out today. that is why i was getting spark on the one coil and not the other. i put a ground on each of the
    right side of the coils. Went for a rip.....MSD RAWKS!!!!!! thanks for the reply if i didn't figure it out today i would have read this tonght and learned that about the coils. you were bang on with your things to check.

  5. #5
    D-Roc Guest


    here is a pic of it all installed.
    Attached Images Attached Images

  6. #6


    Sounds good if there is anything we can do for you please let us know.

  7. #7
    D-Roc Guest


    i got another question about my ignition. it was working perfect last time i rode it. turned it off with the switch, disconnected fuse to the brain's red postive lead. charge battery for 20 min. 8amp park for 2 days. go to start today and no spark. i have been checking grounds and am almost sure they are all good but i will triple check and disconnect and reconnect each one tommorrow. jumped the trigger wires and no spark. the brain's led lights real quick when i turn it on and the fuse makes the typical little spark when installed. tested the common white wire that connects to both coils and it has 3+ volts when cranking. just like my buddies that i checked. i have just spent a good 5 hours checking stuff with my buddies eyes too and none of us can figure it out. it seems like the brain doesn't get it's main 12v on its red lead even though it does as far as i can test it. or the coils are not grounded. i made new wires and added even more grounds to different motor parts and nothing. so here is my question. if one coil goes bad will the other coil spark or does it shut down the ignition. not sure if this even applies because i could not get the either coil to light when jumping the trigger wires. maybe tommorrow with a fresh mind i can figure it out. if you have anything for me to check that would be awesome. oh yeah, i did turn the electric start dip switch off and on and no spark.

  8. #8
    D-Roc Guest


    today i used my multimeter and check for continutiy at all grounds. everywhere i checked it read the same. from battery to head to coil grounds to main grounding stud. Every ground is reading good. i tested a brand new coil for resistance and then checked my coils and got the same readings. i even plugged the new coil into the wires from the brain and grounded it to the cases and no spark from the new coil. I am out of things to check and am guessing my brain might be the problem. If i go to my msd dealer will he be able to order me a new brain box? my buddies brain went dead but the fuse would blow when it was plugged in. My fuse does not blow, and everywhere i checked it has 12.8 volts. led blinks at a rate of once per second if i try to start it or jump the trigger wires. i need some help on this one.:confused1:

  9. #9


    Sounds like you have checked everything you can. You have already tried changing coils and jumping the trigger wires to bypass the trigger pickups so it would lead me to the unit has gone out. You can send it in for testing and if it is with in the one year warranty it will be replaced.

    Thank you
    MSD Powersports

  10. #10
    D-Roc Guest


    i am pissed! not your fault of course and i am thankful for the help. any idea why these units stop working? is there any kind of tips of what not to do with this unit. i mean i ran like 7-8 tanks of gas through the ski so far this year, water is still cold so i wasn't riding in a way that i got real wet and the unit has stayed relativly dry for these rides. i had a professional do the wiring harness and the switch is wired so no voltage will get to the purple wire while charging the battery if it is in the off position. the fuse is always pulled when charging too. my buddies died overnight while just sitting there. i am now thinking the ride on the trailer is somehow wrecking them. i know other guys with extra brains on the shelf because of them dieing. what are we doing wrong? i cannot go back to stock ignition, i will quit riding before that happens.

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