racenaked180sx

Well i have a s14 black top sr in my s14. I bought it from a guy who had no idea what he was doing so ive had some weird issues with it. The other day i was driving home car was running just fine then all of the sudden died. I pulled over it wont start it will crank but wont fire. About 5 hours later we come back with a trailer and for the hell of it i try to start it. It fires runs for about 30 seconds then dies. Same problem continues. We see if its getting spark and nothing. Does anyone have any ideas what could be wrong. Any help would be much appreciated.