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  1. #1

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    Yamaha FX SHO No Spark

    Hey,

    Ive got a 2009 fx sho which does not have a spark.

    Voltage ok to the ignition coils
    Pulser coil checks out ok
    Pulse voltage from ECM to ignition coils ok

    Ski is getting fuel (its unlocked)

    I have an exhaust manifold temp warning on YDIS but Id imagine that should not inhibit spark

    The ignition coil will not fire with the stationary test on YDIS

    Is it possible that my 4 ignition coils are bad? Resistance across the coils on each are about 14 M ohms

    Any help is greatly appreciated.

    Thanks

  2. #2
    TimeBandit's Avatar
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    All four coils bad? Very very unlikely. Rather, if you are sure none are firing (i.e. YDS active test fails), I’d focus on the common-denominator among all four coils. In no particular order, I can think of the following (off the top of my head):

    a) 12VDC supply voltage – in an active ignition state, all 4 coils will have a constant 12v present on all the Rd/Yellow wires.
    b) Ground – All 4 coils have a constant ground present on the Black wires.
    c) the ECU – the computer will pulse a TTL ground signal on the 3rd wire of each coil, every time the respective piston is up (aka there is one lost spark cycle).

    In reference to (a), there is a 14 pin coupler in the harness (Coupler 2) – not sure of exact location. They have connector-like covers (blanks) that can be removed. A bunch of Red/Yellow wires. Pop the cover and verify the pins are not corroded.

    For (b), it’s a 10 pin coupler (Coupler 4). All black wires.

    For (c), you can utilize the YDS active spark tests in conjunction with one of those 12vdc test probe tools. Put the (+) probe wire on (+) battery terminal, then the (-) probe wire on each coil wire harness connector’s signal wire ( B/W, B/R, B/Y, B/G pins). The ECU will pulse a ground, so the probe should flash during the tests.

    As far as the high exhaust temp, are you saying YDS reports the switch is on “CLOSED”? Try unplugging the connector for it, does it toggle to “OPEN”?
    Yes, it shouldn’t affect spark being present, it does limit the ETV and RPMs (aka limp mode).

    Security – I know you stated it’s unlocked, but have you recently cycled the ski between the locked/unlocked states with the fob?

  3. #3

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    Time Bandit
    Thanks for the reply
    a) Yes I have 12 V DC on each coil
    b) Yes I have constant ground on each coil
    c) In the test procedure for the ignition coil, it tells you to test peak voltage at the 3rd (pulse) wire. This I think should be 2.5v peak V DC. I didnt know the ECM pulses a ground so I will check that.

    Yes I cycled the unlock mode. There is no security fob with the ski so I swapped the security box from my fxho to toggle the security light.

    Ill worry about the exhaust temp sensor when I get this girl fired up so.

    Apart from this, I think I will have to buy at least 1 new ignition coil stick to eliminate 4 bad coils.

  4. #4
    TimeBandit's Avatar
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    Sorry, memory fades me... I don't remember the TTL wire pulses pos or neg .. just that its a logic signal that instructs the coil pack to fire. May want to get an analog volt meter on that 1st - pulses might be too brief for a DVM , unless you have an oscope handy.

  5. #5

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    Have you tried new plugs? I haven't yet had the problem with my 09 FXHO, but the MR-1 motors seem to have a common problem. A spark plug or two will just go bad without warning (even brand new plugs). I tried to figure out exactly what goes wrong and came up with one significant observation. The plug will not fire through the electrode... meaning there is no spark to that cylinder. But if you ground the hex side of the plug to the block, you get spark from the side instead of through the electrode. Something like this would explain why you get voltage to the coils, but no spark.


    I also had a similar experience with a VX110. I bought it with a no-spark condition, but it would occasionally start. I swapped the coils from one of my FXHO's and the VX problem was solved. The interesting part is that the FXHO worked fine with the coils from the VX. And when I put the original VX coils back in the VX110, it worked. I still scratch my head over this one. The only thing I can figure is that moving the VX coils between the different cylinders somehow remedied the problem.

  6. #6
    TimeBandit's Avatar
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    I was able to take a look at the service manual ... there's a NPN transistor illustrated inside the coil pack, so you are correct - it's not a ground signal, it will be a positive signal on that 3rd wire. And because it pulses, while cranking the DVM meter will likely smooth it out to a 2.5v reading. So are you getting the 2.5v ?

    Back to lock -vs- unlocked : your method seems a bit unorthodox in swapping the security units between skis ... I can't help but ask, has that worked for you in the past (aka other Yamaha's)? Reason I'm coming back to this topic, because we've historically had folks post-up on this forum regarding weird things in the past regarding Yamaha security, saying skis that are unlocked, yes act like they are unlocked, indicate they are unlocked (aka security led is lite on the dash), even crank, yet won't start runing. The "fix" is usually to redo the fob pairing/programming procedure using the programming dongle, and cycle the ski locked/unlocked at least once. For some reason, this seems to put everything back into sync.
    Now I can't say for certain ... but consider that the security box not only pairs with the fob but pairs with the ECU during the pairing/programming step. And if that assumption is true, while the borrowed box is toggling the Security LED on the dash, it might not be properly unlocking the ecu. { Just spit-balling here }

  7. #7

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    I have the service manual if you need it but can’t help with the lack of spark apart from have you checked TPS, cam position sensor, timing etc? I would query the swapping the security module and fob but burpees it’s logical the programming wand isn’t silly money and there is an fzr in Ireland being broken so a replacement fob and security box might be easy to find

  8. #8

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    Thanks again for the replies guys

    The current tester/ light will not show either a negative or a live on the pulse wire to the coil. As you said Time Bandit the pulse is probably too short for it to pick up.
    When I measure peak voltage on the pulse wire while cranking I get a fluctuating voltage of approx. 3v

    I will get an analog meter today and carry out the stationary test via YDIS on the coil. I would like to see that blip with each pulse from the ECM

    One thing I tested thats got me puzzled. I have 12v between the live and earth wire going to the ignition coil (black - red/yellow). However, when i connect my test light to the (+) side of the battery and test the earth wire on the coil plug, I dont get an earth. How is this possible ?

    I take on board what you say re. the security box. I put engine supports in an fx a couple of years ago and after installation it woud crank but not start until I cycled the unlock light. I never used a box of another ski but I asked the question on GH before and I was informed it would work but maybe you are correct. I just want to eliminate other areas before i buy a new fob.

    Thanks again

  9. #9
    TimeBandit's Avatar
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    Really no need to get an analog meter, because setting your DVM to "peak voltage" is the correct procedure as per service manual.
    The service manual states roughly 2.5v peak while cranking. You got roughly 3v. Little high?? Maybe. Why? Hmmm.

    Good-call on the test light to the coil ground - the failure might indicate an earth ground issue after-all.
    Voltage checks alone - they can be false-positive at times. Remember, measuring the presence of voltage is just half of the Power equation ... current-flow is the other.
    When you probed the voltage at the coils, you are seeing a potential - yes. However, even a very poor earth can still allow just enough current by to build up to the expected voltage potential.
    Inversely, using the test light to test the coil earth, you are testing circuit current (aka driving the test light). In this case, a poor earth ground might not be enough to power the light.
    Try this: simply repeat both of your tests again ... yet perform them at the same time (keep the DVM probing the coil power while you also perform the test light again. See if that DVM voltage diminishes the moment when you attach the test light (-) to the coil's black wire.


  10. #10

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    TimeBandit,

    Great idea. I was thinking the along the same lines (voltage potential) but I hadn't thought of doing both tests simultaneously.

    Also when I measure peak voltage at the pulse wire of the injector it is not giving a smooth 3 volts, rather a fluctuating voltage but I figured that was normal as it is not a constant supply.

    I wonder if i hooked up an injector noid light to the pulse wire of the ignition coil should I get a flashing light while cranking ?

    Thanks again bud

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