If you are having fuel supply problems, you should still be able to get it to turn over.

If it's flooding, close the needle valve, and spin it for a while. The excess fuel should clear out, and it will start up.
If it's too lean, prime it more, it should start.
If it runs for a few seconds then quits, maybe you have a tank problem.

If you can't get it to run at all, it's probably not fuel.
When I get stumped, I look for carb air leaks, try a new glow plug, then try a friend's glow driver.

Good luck.

Ken