how can i clear airlock on a 40 riello oil burner?

yip ran out of oil,i took red metal cover off,the pump on left had a screw in the middle at top,i loosend this and released a large amount of air,i re tightend the screw then loosened it a bit and then hit restart(red button)oil is coming out, no air, but will not fire up after 10 secs,on the top of pump to the right is a small allen bolt,i am at my wits end as i'm not mechanily minded,could some one please help me to get it running again.