1997 Nissan Sentra My car won't start

I had my car out yesterday to do errands and it was driving just fine. I have noticed no problems with it whatsoever--no strange noises, no hesitation, nothing that would make me think something was wrong. I tried to start it this morning and it turns over, but won't start. We've checked the spark plugs, checked for spark, looked at the rotor and cap, everything's clean. We also pulled the fuel line off the fuel filter and there is definitely fuel shooting out freely. Wondering if the timing belt might have slipped or the fuel injectors might be clogged. It might be turning over a little slow, but seems fairly normal. We tried pumping the gas a little and it almost started then.