I was experiencing similar issues, and the following easy fix solved everything: Follow the standard start up procedure, mixture full rich, throttle fully opened, turn on the prime (high) pump for about a second, then switch to the boost pump, pull back throttle to about a quarter open, now turn the starter on. And here is the trick, if the plane doesn't start, make sure you have the ignition cranked up to start, and slowly shift the throttle back or forward. Doing this solved my start up hassles. I'm sure the developers will fix this bug with the next update.