SBT Jetski Engines, Parts & Accessories

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  1. #1
    Aug 2004
    Page, AZ.

    Default Closed Throttle Runaway

    i have a gtx with a new 951(silver). the problem is that both of the times that i ran it, it ran fine for 5-10 seconds and then it took right off to full throttle rpm, and the throttle was never touched. i've heard this refered to as "closed throttle runaway" and it is caused by an air leak. the first time i pulled the plug caps and it died, the second time i pulled the caps and it ran for another 10-20 seconds. any insight to this problem will be greatly appreciated

  2. #2
    Nov 2003
    Glendora, CA

    Default Re: Closed Throttle Runaway

    First off, pulling the plug caps had noting to do with the motor shutting off.
    To kill the motor, pull the choke and or open the throttle to full open with the lanyard off.

    It is known as glowplugging. When the air fuel mixture is too lean, and the throttle plates are partially open, a 951 will glowplug in a heartbeat. Glowplugging describes what happens to the tips of the sparkplugs when they get too hot and self ignite the fuel.

    If the throttle cable was installed too tightly as to not allow the plates to fully close with the idle screw fully backed off of the stop and a little extra slack in the cable, it will glowplug on you. After installing a motor, the first thing to check is the throttle cable for slack. Second, turn down the idle screw so that the motor barely idles, then start screwing it back in until you see around 2600 rpm on the tach. If you still cannot control the engine speed, then try opening the low speed adjuster to feed more fuel into the motor. If nothing works, start looking for an air leak, the most common on a 951 is somebody forgot to connect the hose ( or hoses ) to the cases from the Rave solenoid, or the fuel pump.

    Never run the motor without water for more than a few seconds.
    Bill O'Neal <br>
    <a href=""

  3. #3
    Aug 2004
    Page, AZ.

    Default Re: Closed Throttle Runaway

    What are the stock carb settings for the low and high speed adjusters?

  4. #4
    Jun 2004
    Glendora California

    Default Re: Closed Throttle Runaway

    Zero on the highs and 1.25 on the lows give or take a little.
    Bill O'Neal, owner of Watercraft Magic in Glendora California,

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