03 cavalier w/ no fuel at fuelrail or in lines (fuel pump)

vapors go from tank to canister but not back to tank

relieve fuel pressure from the fuelrail then try again

I would say fuel pump but u should try cleaning throttle body 1st its easy takd ya 30min and only like 8$ for cleaner u can watch how to videos on you tube

I have an 03 cavi and it wouldnt start so i took the fuel pump out and pluged it back in and turned the key to the on position and the fuel pump works so i think it might just be the pick up filter. Im going to take the fuel pump appart and see whats up.

Generally when this happens all the time the fuel pump relay has gone bad. Upon starting any GM car up the fuel pump operates off the third wire on the oil pressure switch. When the oil pressure reaches operating pressure which happens in a few seconds the computer shuts off the current from the oil pressure sending unit and opens the circiut flow to the fuel pump relay. The relay will run ythe fuel pump until you shut the engine off. Replace the fuel pump relay and you shall have a good running car again

fuel pressure is your problem here. dirty or restricted fuel filter may be causing your problem or you may have a tired fuel pump. (if it stays running) if it dies you may have a bad pump. you can never go wrong with replacing the filter first. it is recomended maintenace.

It sounds like your fuel filter has gone it life time and now to dirty to permit the proper fuel flow if any.
Start with checking the fuel pressure at the shredder valve, you should have over 45 PSI i believe but could be wrong, can not remember could be 60 PSI. 
If you can not check the fuel pressure, change the fuel filter first then see if it starts. If it does not, then it may be a bad fuel pump and need to be replaced. The fuel pump is electric and have a life time too and it may be at it's end also.
Good luck and keep me posted.

• see if you can hear the fuel pump click over when you turn it to start position! this may be a fuel pump?

try a tune up

you need to find the fuel pressure release around the fuel rail press the little tab when the car dies. If there is no fuel coming out from that point, your fuel pump is going.