It is possible that there is voltage being applied to the start button wire. Disconnect the start button wire at the solenoid and turn key on and check for voltage. There should be none. If there is then I would check the start button to see if it is stuck or there is a short to voltage somewhere in the circuit. If there is no voltage then make sure you have the start button wire on the correct terminal on the solonoid. Also check to make sure you have a good ground for the solenoid to the frame contact area. Good luck......