check your fuel tank for a kinked or plugged up pick up line.check fuel lines for pin holes or kinks anywhere in system.inspect glow plug element for deformation...if so replace it,ensure copper ring seal is under glow plug.ensure you have proper sized prop installed.ensure head screws are tight as well as backplate screws.main needle should be turned out two and one half to three turns out.fire up engine.if problem persists after these steps....check to see if carb spraybar is blocked by removing needle,hook up clean fuel line and blow through it gently,spay bar should pass air,if in doubt remove carb from engine and soak in alcohal for a couple of days to loosen gunk in spraybar and try to clear it out.reinstall eng and fire it up as directed above.happy flying.