1994 Honda Civic Doesn't Start

I resently bought a 1994 honda civic from a private owner, after having the car for less then a week the car will not start. I have power inside the car, the lights, radio sunroof and windows all work. But when I start the car it sounds like it's trying to start but won't stay started. I changed the fuel filter and timing belt. I checked all fuses and hoses and nothing seems to work. Does anyone have any other suggestions before I put too much money back into this car?