why will my sr take long to start?

hello can any1 help i gt a sr and you have to electric strat it for ages then you will hear a serten sound then it will go to tik over and then start. and somtimes wont start. when it does it will go as long as i keep reving it will be ok then just cut out at full throttol an my injection cheak light will flash can any1 help
and if it dnt start when i electric start my injection chek will come on