I was told that my alternator went out I replaced it and it still would not start. I've read further into it and I saw that it may be the crank shafts sensor I am waiting for it to arrive to install it but if that doesn't work what could it be?
Also it started and ran for about 10 minutes after the alternator replacement but died. I am getting fuel pressure through the fuel rail.

 

Does the starter turn (motor cranks)? If so, you can rule out the starter motor and relay. You can also rule out the battery/charging system as the alternator would make no difference on starting your car.

Crank position sensor (cps) is a likely culprit. Pull out a spark plug, ground it against the engine block, and have someone watch for spark while you crank it. If you have spark, probably rules out CPS. If you don't have spark, it could be the CPS or the neutral safety switch if you have an auto trans.

 

Well since I already have the sensor ordered I'm going to replace it and hope that's the problem my battery is dead so that's why I'm not testing for the sensor to be the problem. But yes when the battery is charged the engine does crank. I thought it was the alternator because if the alternator was the problem the car would just be running of the battery until it dies.

 

^
This is more than likely the issue.

 

I jump started the car after I replaced the alternator. I let it sit and charge it didn't start until the next day. When it did it stayed on for 20 minutes at most then died. The battery isn't the issue and I think the alternator was because that is the charging system and if that is not working then the car is running off the battery until the battery is dead.

 

Slap a fuel pressure gauge on that hog and see what you have key on engine off, with it running just for 3 seconds.