1999 Ford Escort Won't Start

I just purchased a 1999 Escort LX, I've had it a week and now it won't start. It ran fine when it runs. It wouldn't start one time before and after several minutes it started. I am getting a signal to the injectors, though I had it on the lowest setting on the multi-testor & it barely registered. I can hear the fuel pump coming on. The fuel pump cut-off switch is fine. I am trying to find the fuel pump relay and can't find it, but I know the pump is getting power. I haven't checked the pressure at the fuel rail yet and I havn't changed the fuel filter (the car still got about 35 MPG). I was wondering if it could be the crankshaft position sensor, the fuel filter or the fuel pump. What should my next move be? I don't think there is any fuel getting into the engine because I am not getting any fumes out of the exhaust.