surf still runs with ignition off

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HI all,i own a 94 surf kzn130 which developed this fault today.Starts and runs fine but when i turn of the ignition off and remove the key the engine keeps running.A phone call to a friend leads me to believe the fault could be the fuel stop solenoid.Would appreciate your thoughts on this,whether you agree with this our think it might be something else.ATB Ste