My 2001 Sentra will crank, but not start. Belts move, and the fuel pump makes the humming noise when I turn the key slightly, but I haven't been able to start it. I haven't gotten the chance to check spark plugs, and I have researched this but can't find a definitive answer. I thought maybe it was the key-less remote because the battery is dying/dead in it and I was going to replace it, and one of my relatives had an issue with their car not starting because of the security system. Before the car had this problem, I noticed for about a month whenever I started the car, it seemed a little weak and would sort of vibrate in park for about 10 seconds before smoothing out. Just before it wouldn't start, I moved it out of my friends driveway (started it, moved it about 30 feet and then shut it off), and then an hour or so later, it wouldn't start. Is it something with the fuel? Not the fuel pump, but maybe it's not getting to the engine?