i was wondering because my cousin says it could be my fuel pump that is causing my car not to start. he replaced one on his teg and now it starts fine.

the thing is, most of the time my car will start up with no problem and run without dying. if the fuel pump can withstand that then it should be fine right? would it most likely be the main relay that is causing my pump to not come on sometimes? .. what is the difference between the fuel pump relay ad the main relay? and where is it located in a 92 civic? thanks