Lately when trying to start my 98 Jeep it doesn't start right up like it used to. It will crank over for a little while, I'll stop and try again then it will start. I've tried keying it on for a moment then turn it over and it will start. So I'm thinking maybe fuel pump. Is there any way to tell if its going bad? I would like to fix it before I'm stranded somewhere. Or could it be something else?