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  1. #1

    Help again stx15f starting problem

    Hey guys, I need your help again!

    Ok so i was on the jet ski for three hours and i wasn't pushing it because i just put the engine together and it has new oil and everything. so we are driving and its all good driving smoothly and then when we are about to go to the loading dock the engine just dies, it turns off, i tried turnign on the engine but all it would do is turn but not start. So i towed it to shore checked everything everything seems fine, no water in the hull just couldn't understand why it wouldn't start. so i took it home and i was checking everything maybe spark plugs? so i changed them with new ones and made sure that the coil pack was giving spark and they are. then i took out the injectors to see if its giving me the fuel i need and they are as well. check all the connectors to see if all connections are tight and how they should be and they all are, i am just stumped on what it could be now.

    The only thing i could think of is the ecu or the regulator, is there anyway i can check that these are working properly?

    Also guys here is a video that i uploaded so that u guys can see what the problem i'm having sorry for the night time but im working all night lol

    the only way it will stay on is if i give it some throttle. and when holding the throttle it runs really rough.

    SOrry for the long story but want to give you guys full detail so u guys can give me your expertise.

    Thanks for the help


  2. #2
    Is this the same ski that blew a rod through the crankcase? If it is I'd be thinking real hard about if this is a rebuild assembly mistake or when the engine blew up was it a contributing factor (if the thing vibrated apart). The unit has an air pressure and throttle position sensor with resistive values you can check with an ohm meter. You can check the fuel pressure with a wet gage(about 40psig or better).

    There are cautions when installing or removing the DFI parts like making sure the battery is disconnected first. All electrical parts should be hooked up or disconnected with no power to the ignition system.

    Did you try the self diagnosis dealer mode for error reporting?

  3. #3
    Yes this is the same one that blew a rod
    I would have to go to the dealer to get the diagnoses. I don't know what is going on very frustrating

  4. #4
    Down load the manual.

    Check the resistance of various DFI components as per the manual using noted precautions and an ohm meter. The dealer mode is accessable but you may need to do it while it is running ruff with a second set of hands?

  5. #5
    Dfi stands for? Just want to tell my mechanic

  6. #6
    It's the fuel management system (digital fuel injection)

  7. #7

    help needed.

    k so i've been helping azzo working on his jetski. like he said, we have fuel pulsing at the injectors, and spark. If we start it and hold the throttle open it will run, but not smootly like it should. i have a hunch that one of the sensors is at fault. Also i noticed smoke coming out of the intake after shut off. This engine was not rebuilt by us solely. An uncle of mine that has over 40 years of experience in engine rebuilding did the majority of the rebuild so a fault during that process is unlikely. After the rebuild the machine ran perfectly fine for days out of the water with a hose, and after just 3 hours in the water in shut off on him. Feels like its struggling for air, or something. Please help. Thanks


  8. #8
    The cam chain might have jumped?

  9. #9
    Formerly Ultra250 TN Aquaholic6801's Avatar
    Join Date
    Feb 2007
    Old Hickory,Tn
    +1 sounds way out of timing..........

    Quote Originally Posted by rotortiller View Post
    The cam chain might have jumped?

  10. #10
    k, so after working on the jetski for another few looong hours, we removed and unplugged the air pressure sensor. We cranked it and it started and ran. Given that the pressure sensor was out, the idle was all out of wack. however, after reinserting the sensor, the idle sort of stabilized, but continued to run. We then tried plugging in the connector to the sensor and engine shut off. So i am guessing that the pressure sensor is messed up. Looking for some input as well as a place where i could purchase one for cheap. Thanks for any help.


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