If your motor has a VRO (oil / fuel) injection pump but you have disabled its function, make sure to unplug the wiring from it.
When premixing oil + fuel such as 1/50 or 1/33 there is no need for the VRO. On older motors many people bypass the oil injection feature for the sake of reliability.
If the VRO is still plugged but not in use the motor will not start.
