1995 240sx starting issue??

[240sR4drifting]

Okay, so my 240 starts sometimes but if I run it for a little while or just a minute, and shut it off and try to restart it it doesn't...it doesn't crank or anything so I'm assuming it has to be something to do with my starter? Maybe my relay. If I keep trying to start it it sometimes eventually starts up, and when it does its fine, so I'm not really sure what could be the problem, I might pull off my start and see if its good. Just let me know what you all think, all help is appreciated
-Thanks!