If the engine is cranking normally, the generator is not the problem. The battery is charged if it is cranking the engine, and that is the job of the generator, (alternator). The engine WILL stop running after up to an hour of the start of a generator failure, depending on how many electrical things you have turned on, but then the battery will be too run down to crank the engine.
It sounds like you have some other problem. If you indeed have spark, that rules out a lot of possibilities. Fuel pressure at the engine can be misleading. You also need injector pulses to spray the fuel into the engine. Also, the Engine Computer turns the fuel pump on during engine rotation, (cranking or running), and it knows that by the signals it gets from one or two sensors. If one of those sensors has failed, the fuel pump may not be running during cranking, but the pump will still run for one second after turning on the ignition switch. That one-second burst can be enough to develop fuel pressure even though the pump doesn't run after that.
Besides spark and fuel pressure, you need compression and proper timing of all the events. A problem with compression is not likely to develop in such short order while driving unless something broke. A problem with timing is much more common. A timing belt that jumped a few teeth is the first thing to look for.
You also need to have the diagnostic fault codes read and recorded. They will never say to replace a part. They indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. It is important to not disconnect the battery or let it run dead because the codes will be erased and that valuable information will be lost.
Saturday, June 18th, 2016 AT 9:53 PM