What you are calling the front CPS is a _Camshaft_ sensor. This is just tells the computer is cyl 1 is on the compression or exhaust stroke and on the CIS M104 to confirm the intake cam advance is working. For the later ME M104 is it used to sync the injector pulses for a smoother idle / diagnose miss fire for the OBD2 system. With either motor, the engine should still start with a non working cam sensor.

Do you have a lab type oscilloscope? If so hang it on the rear sensor, this is the _Crankshaft sensor. This tells the ignition when to fire and gives RPM info to the ignition module and other systems.

I'd hang a test light on the fuel pump to see if it is shutting off. Another test would be to manually run the pump for 30 sec then, while leaving it powered up, try to start.