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  1. #1
    Dg1148's Avatar
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    Blown motor, lean fuel. Possible causes.

    Long story short, got my gp1800 back from the dealership with a brand-new motor. Swapped my retainers from previous head and dropped in. Running stock tune for the break in period. Performance mods, 4" intake to front compartment, fizzle IC, ribbon delete, Riva waterbox. Within an hour of breaking in, correctly, smoke was coming from exhaust. Shut it down. Towed back to dock went straight to dealership. They tore into it and came to the conclusion with their findings that cylinder 2 and 3 had signs of lean fueling. They are not wanting to submit to Yamaha again because they don't know why it ran lean other than I have an intake and intercooler. Is that alone enough to cause a motor to blow on stock tune?


  2. #2
    ptscon's Avatar
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    Get the fuel injectors flow tested.

  3. #3
    Ale's Avatar
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    with your mod you have increased air flow to your engine
    if you do not increase fuel with a tune...
    and if you do not monitor AFR...
    these are the results....

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  5. #4
    unclemd's Avatar
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    Quote Originally Posted by Dg1148 View Post
    Long story short, got my gp1800 back from the dealership with a brand-new motor. Swapped my retainers from previous head and dropped in. Running stock tune for the break in period. Performance mods, 4" intake to front compartment, fizzle IC, ribbon delete, Riva waterbox. Within an hour of breaking in, correctly, smoke was coming from exhaust. Shut it down. Towed back to dock went straight to dealership. They tore into it and came to the conclusion with their findings that cylinder 2 and 3 had signs of lean fueling. They are not wanting to submit to Yamaha again because they don't know why it ran lean other than I have an intake and intercooler. Is that alone enough to cause a motor to blow on stock tune?
    I thought I seen a few posts that just by removing the ribbon some people reported running lean on a couple cylinders with the SVHO engines when not running a tune. So by adding the intake and IC it is quite possible that a lean condition could of caused this. I was also told that removing the ribbon causes the fueling to individual cylinders to be thrown off slightly and by leaving the ribbon in it provides more balanced fueling and air to each cylinder. I have a ribbon delete and pretty much the same mods that you explained but I choose to leave the ribbon in on my application for that reason and to also provide protection if I ever have a supercharger failure. I'm no expert by any means and gather all my information from the GH community so someone else should chime in and correct me if I'm wrong.

    Thanks

  6. #5
    stifun's Avatar
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    Quote Originally Posted by unclemd View Post
    I thought I seen a few posts that just by removing the ribbon some people reported running lean on a couple cylinders with the SVHO engines when not running a tune. So by adding the intake and IC it is quite possible that a lean condition could of caused this. I was also told that removing the ribbon causes the fueling to individual cylinders to be thrown off slightly and by leaving the ribbon in it provides more balanced fueling and air to each cylinder. I have a ribbon delete and pretty much the same mods that you explained but I choose to leave the ribbon in on my application for that reason and to also provide protection if I ever have a supercharger failure. I'm no expert by any means and gather all my information from the GH community so someone else should chime in and correct me if I'm wrong.

    Thanks
    Well, I have a ribbon delete and free flow with no ecu tune, should I be concerned?

  7. #6
    Quote Originally Posted by stifun View Post
    Well, I have a ribbon delete and free flow with no ecu tune, should I be concerned?
    Not to freak you out but thats why i have not deleted my ribbon not to say it will for sure run lean just saying it was a concern if mine. I will get the ribbon deleted eventually after the warranty is up but i will get a tune as well.

  8. #7
    unclemd's Avatar
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    Quote Originally Posted by stifun View Post
    Well, I have a ribbon delete and free flow with no ecu tune, should I be concerned?
    Lots of people run it without issue so I wouldn’t be over concerned and this has been a proven mod for years. I might be just overly cautious I’m just stating what I have seen in a couple posts but they may not have any merit. The only way to know for sure is to monitor your AFR but with little Mods like you stated I wouldn’t worry. When you start adding an aftermarket IC and Mods like that I would be concerned about running stock tune.

    Like I said I only get my information from the GH community and no way am I an expert in tuning.

  9. #8
    Dg1148's Avatar
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    I'm just at a loss that this happened when this common of a setup hasn't given anyone else problems. I was cruising around 40/45, not even close to WOT when I noticed the smoke and it starting to feel different. I just can't see it being that extreme of a lean condition at that speed.

  10. #9

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    you NEVER went wot? if thats the case then its a problem on their end. no way even if you were lean that you put enough load to hurt the engine. and if im not mistaken they can plug into the ecu and see that you never went WOT.

  11. #10
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by Dg1148 View Post
    ... gp1800 ... brand-new motor.

    Swapped my retainers from previous head and dropped in.

    Running stock tune for the break in period
    .

    Performance mods, 4" intake to front compartment, fizzle IC, ribbon delete, Riva waterbox.

    Within an hour of breaking in, correctly, smoke was coming from exhaust. ... cylinder 2 and 3 had signs of lean fueling. ... they don't know why it ran lean other than I have an intake and intercooler.

    Is that alone enough to cause a motor to blow on stock tune?
    This seems strange, to make all those changes to the air flow through the engine, yet run with a stock tune during engine break in?

    Perhaps you considered using the stock tune to be ‘safer’ than doing engine break-in with a correctly selected aftermarket ECU tune? Yet with multiple modifications to the air flow (both intake and exhaust, plus a better intercooler) the stock tune may have been operating the engine well outside the desired parameters for ‘safe’ fuel:air ratios.

    Aftermarket ECU tuning is not just about adding power and speed. Correctly configured ECU tunes also compensate for changes (improvements/increases) to engine air flow, intake air temperature and cylinder to cylinder variations indices by those changes.

    Your engine was flowing more air at colder temperatures yet the stock tune may not have been able to enough additional fuel to match the additional air? Or match indicted changes in cylinder to cylinder air flow variation...

    Clearly in this case the damage has already been done. I would suggest that the ‘safest’ approach with a newly replaced (or just brand new watercraft) engine would be to run with stock tune and stock engine air flow during the break-in period (and perhaps until the initial oil change has been done). That way any problems related to infant engine failure (and warranty eligibility) are not muddied by the presence of aftermarket changes.

    When airflow changes are being added, an aftermarket tune correctly calibrated to match those changes may well be safer than forcing the engine to run a stock tune with non-stock airflow conditions.


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