Five Steps to Starting an Older 2-Stroke Outboard Engine

1. Engine tilted fully down (this makes it easier for fuel to get to the carburetors).
2. Squeeze primer bulb till firm.
3. Advance throttle in neutral to 2/3s.
4. Turn key on, push to choke (or pull out choke) and crank at same time.
5. Release choke, return throttle to neutral after ignition.

Also, make sure the tank is vented. If it's a built-in tank, make sure the vent fitting is not partially obstructed by an insect nest or wax or something.