When you say it is "firing" what does that mean to do you, what is it doing? Does it have spark at the spark pugs or not? Does it have injector pulse?
This usually indicates no crank sensor input and will also result in no fuel pump operation, no injector pulse, and no ignition spark at the spark plugs.
Fuel sync can be way off and it will usually still start and run if everything else is working correctly. All this does is let the PCM know where cylinder number one is at so it knows the firing sequence of the injectors. If the distributor pickup coil (cam sync sensor) does not work at all or is unplugged it will cause a no start issue, but there is a test in the older service manuals to unplug the distributor and jump the sensor wire and ground wire together, on and off, and it will allow the engine to start.